Why on earth would it be important whether or not a being didn't have to practice Buddhism to become a Buddha? It matters little to deluded sentient beings if there is an inconceivable overlord who doesn't need to practice six perfections to become a Buddha. Deluded beings need to practice six perfections either way.
When you postulate an overlord who has always been enlightened then you just pass the puck of "first Buddha" to his first student. If the Buddha has always been enlightened, he is not a Buddha, as he has never "woken up," always having been "awake." So the "first Buddha" just becomes the student of this master. The whole things sort of falls apart, because the Buddha is no longer the Buddha.
The only way it would become "important" that such a being existed was if we were that being, as hinted as in your OP, and all I can say is that if you think everyone is primordially enlightened as the primordial Buddha, then there is no need for Buddhas. It sounds like the OP at worst is just looking for an excuse not to practice six perfections and to declare the work done before it has been completed or at best is trying to make an argument for Theistic Buddhism.
The question of the Buddha's parinirvana that you attribute to the Lotus Sutra is already present in East Asian Madhyamaka:
Now, names do not arise in a vacuum, designations do not arise by themselves. The designations found in the sutras, “nirvana with remainder” and “nirvana without remainder,” must be, respectively, the true name for the return to the root and the wondrous designation for the way of spirit. Allow me to speak of these in turn.
When the Tathāgata attained great awakening and his Dharma body was established, he bathed in the pure waters of the eight kinds of liberation and found repose in the verdant grove of the seven limbs of awakening. After cultivating wholesome deeds for innumerable aeons, he at last shook off the dust accumulated over time immemorial. The three illuminations mirrored within him, his spiritual glow illuminated without. Having at first armed himself with the bodhisattva’s resolve, finally, in universal compassion, he delved into the world of human distress.
Above, he held on to the root of mysteries; below, he reached out to lift the weak and the forlorn. He strode beyond the threefold world; he trod alone into the Great Square. He opened up the eightfold path, a road for the multitude, broad and gentle. He mounted the spirit-steed of the six ṛddhipādas and rode the royal carriage comprised of the five vehicles. At will he crossed the border between life and death, joining with beings as they wandered in samsara, his way harmonized with all, his virtue reaching everywhere. He plunged to where the root of manifestation gives origin to being, and fully activated the wondrous function of the mysterious mechanism. He draped the firmament of vacuity beyond all borders, and stoked the fire of omniscience to illumine the darkness. He was ready to erase his traces from the nine abodes of being and immerse himself forever in great vacuity, yet there remained in him a residue of karmic conditions, traces not yet effaced. This residue lingered on like a cloud-soul, and his sagely wisdom endured.
This is nirvana with remainder. In the words of scripture, “Myriad afflictions are no more, as though transmuted into pure gold, yet his numinous cognition alone abides.”
When the Perfect had taught what had to be taught, he extinguished forever his numinous illumination and vanished into the boundless and nonmanifest: this is nirvana without remainder.
Of all forms of disease, none is greater than that of having a body — he extinguished the body. Of all forms of torment, none is more severe than that of having a calculating mind — he erased it and submerged in the vacuous. The mind is taxed by the body; the body is burdened by the intellect. The two pull each other, turning like a wheel on the endless road of misery. It is said in a sutra, “The intellect is poison, the body is shackles. Because of them the abysmal silence of liberation remains beyond reach; they are the cause of all tribulations.”
The Perfect turned his body into ashes and extinguished his intellect, he relinquished his form and discarded his reason. Within, he abandoned the stirrings of illumination; without, he put to rest the basis of misery. Transcendent, perfectly free from all existents; boundless, he became great and vacuous. Tranquil, inaudible, clear, non-manifest, mysteriously gone forever into a destination unknown. When a lamp goes out its flame is extinguished, the oil and the flame gone all at once.
This is nirvana without remainder. In the words of a sutra, “The five aggregates are no more, like a flame extinguished.”
This being so, nirvana with remainder can indeed be called “the nameable,” while nirvana without remainder may be called “the nameless.” With non-nameability asserted, partisans of emptiness will be gratified to find sanction for their belief that in the all-pervading silence; with nameability affirmed, those concerned about virtue and morals will have the Sage's actions to look up to as their model. Such are the teachings imparted to us in the authoritative scriptures, the tracks laid down by the sages of old.
“Considered from within, neither is it existent nor nonexistent; viewed from without, language fails to approach it. Seeing and hearing do not reach it, the four kinds of formlessness obscure it even further.”
When lovers of virtue hear this doctrine they will despair; when proponents of emptiness hear it they will be left without a refuge. It describes a state no different from that of someone who, even though his eyes and ears are as obtuse as when he was still in the womb, and for whom the heavenly bodies are obscured beyond the most distant clouds, nevertheless attempts to pronounce on fine distinctions in musical notation and to discuss the diverse appearances of the astral phenomena. He knows only to banish the Perfect outside of being and nonbeing, to sing lofty praises of what is beyond forms and names. Yet all the while his words lead nowhere and block the recondite path, instead of revealing it. Though he ponders on them intently, they do not bring him peace. Are they really the light in the dark chamber, the wondrous sound that restores hearing to the deaf?
The terms “with remainder” and “without remainder” are only external appellations for nirvana, conventional designations for the divergent modes of the sages’ responding to things. Those who cling to concepts will be bound by concepts; those who are attached to forms and images will be constrained by forms and images. Names reach no further than the definable; forms stop at the square and the round. But there are things that “square” and “round” cannot capture, and things that concepts cannot convey. How could names express the unnameable, how could forms truly capture the formless?
It is correct to say that the terms “with remainder” and “without remainder” describe the two modes establishing the teaching, through action and through quiescence, or the two modes of the Tathāgata’s supreme activity, the manifest and the hidden. But they do not refer to, on the one hand, any dark mysteriously quiescent principle beyond words, or, on the other, to some wondrous workings of the Perfect in the center of the maṇḍala. Have you never heard of “correct contemplation”? Vimalakīrti said, “The way I see the Buddha is as one with no beginning or end, one who has transcended the six senses, who has left the triple world behind, one who is neither somewhere nor nowhere, who neither acts nor does not act, one who can neither be cognized with consciousness nor known with knowledge, one beyond language, one whose mental operations are extinguished. To view in this manner is called to contemplate correctly; to view otherwise is to not see the Buddha.” As "The Radiance" (a Chinese title for the Pañcaviṃśatisāhasrikā) says, “The Buddha is like empty space. He neither comes nor goes. He manifests in response to conditions, he dwells in no definite location.”
As for the Sage’s position in the world: silent, vacuous, he does not grasp, he does not contend, he leads without asserting himself, he responds to each stimulus without fail, like an echo in a dark valley or images in a clear mirror. Face him, no one knows from where he came; follow him, no one knows where he goes. He emerges suddenly into being, suddenly he disappears. The more active he is, the more quiescent; the more hidden, the more manifest. From the darkness he emerges, to the darkness he returns; his transformations follow no predefined pattern.
As for these appellations, they are established to indicate the various modes of sagely response. When the Sage manifests traces, we call this “arising”; when he makes them vanish, we call this “cessation.” His “arising” is referred to as nirvana “with remainder,” his “cessation” as nirvana “without remainder.” All along both appellations — “with” and “without remainder” — remain rooted in the nameless. Surely the nameless will take any name? Thus, the Perfect becomes a square when he inhabits a square, a circle when he stops in a circle, a deva when among devas, a human being when among humans. To become a deva or a human being in accordance with circumstance is surely not something that devas or humans could do. It is precisely because he is neither a deva nor a human that he can become one or the other.
As for his transformative rule, he merely responds, he does not act deliberately; he follows the causes, he is not being charitable. Not being charitable, his charity is perfect; not acting deliberately, his action is unsurpassed. He is unsurpassed in his action, yet he goes back to ordinary accomplishments. He is perfect in his charity, yet in the end he returns to the nameless.
It is said in scripture, “The Bodhimārga cannot be measured; it has no top, no bottom, it is expansive, and deep without limit. Great, it envelops Heaven and Earth; miniscule, it penetrates into that which has no openings. Thus it is called ‘mārga.’” Clearly “being” or “nonbeing” cannot capture the path to the uncreated (asaṁskṛtagāmimārga).
Yet when the deluded consider the Buddha’s extraordinary feats in the world they assert his existence, and when they reflect on his passing into cessation they assert his nonexistence. Yet how could one, from within this realm of being and nonbeing, from this domain of delusive thought, adequately express his difficult Dharma and adjudicate on the sagely mind?
I say that the Perfect is quiescent, imperceptible, without any external form. The hidden and the manifest aspects of his being originate in one source. Although present, he does not “exist”; gone, he does not “nonexist.”
How so? The Buddha said, “There is no birth realm where I am not born, but I am never born. There is no form that I do not take on, but even while embodied I do not have a body.” This means that though present, he does not “exist.” It is also said in a sutra, “The Bodhisattva entered limitless samādhis and saw all the Buddhas of the past who had passed into cessation.” Also, “He entered nirvana, yet did not enter parinirvāṇa.” From this we know that, while vanishing, the Tathāgata does not simply nonexist. Not nonexistent: while nonexistent, he exists. Not existent: while existing, he does not exist. Existing, he is nonexistent: therefore “being” cannot be attributed to him. Nonexistent, he exists: thus “nonbeing” likewise does not apply.
Hence, we can conclude that nirvana transcends the domain of being and nonbeing, and leaves the path of names and images far behind.
Yet the Sage saw the body as the source of the greatest distress, so he extinguished the body and returned to nothingness. He saw the unawakened mind as the source of the greatest torment, so he eradicated it to submerge in the vacuous. Is this not a violation of the Sage’s spiritual perfection, an injustice to his profound teaching?
It is said in the Flower Garland, “The Dharma body is formless, in responding to things it takes on particular shapes. Prajñā has no knowledge, it just illuminates in response to objects.”
As the Sage hastens to engage the myriad events, his spirit stays unperturbed; as he responds to each of a thousand exigencies, his mind remains unruffled. In movement, he is like wandering clouds; in repose, he is like the valley spirit. Would he tangle his mind in discriminations between “this” and “that,” or his emotions in the distinction between “movement” and “repose”?
Since he does not bring a deliberate mind to his movement or stillness, he does not show discrete forms in his coming and going. Since he does not impute a discrete form to his coming and going, there are no shapes that he cannot assume. Since he does not bring a deliberate mind to his movement or stillness, there are no stimuli to which he fails to respond,
What I mean is that the Sage’s “mind” arises in response to the deliberate mind of beings; his “forms” emerge in response to the existing forms in the world. Since his forms do not emerge from his self, even if he were to tread on molten rock and metal he would not be burned. Since his mind arises not from his self, even though he delves into everyday affairs he remains unperturbed. Could the tangles of conventional distinctions like that between self and other constrain his self?
Thus the Sage’s wisdom embraces all things yet it is never belabored; his bodily form fills the eight directions but this brings him no distress. If you add to him, he will not overflow; if you subtract from him, he will not be lessened. How could anyone take literally the story that he contracted dysentery on the way to Kuśinagara, that his life ended under the twin trees, that his mind ceased in the regal casket, and that his body was cremated on a pyre? Yet all the while the deluded, investigating the traces of his extraordinary responsiveness, cling to the evidence of their eyes and ears. Carpenter’s square and ruler in hand, they go about trying to measure the Great Square: they want to find the Perfect belabored by knowledge and distressed by bodily form. “He discarded being to delve into nonbeing,” they claim, and then assign to him the corresponding names.
Surely what they do is not picking words of subtlety from the realm beyond speech, or pulling the root of mystery from the vacuous field.
