I meant to write 2500 years ago.
I thought this sutra was in the original words of the Buddha.
Are there any original texts which are actually his words?
Not in the sense that they are an exact verbatim transcriptions of what he said. The oral traditions - there were likely many regional versions - had very gradual accretions or edits over time themselves. We are talking about generation after generation of oral tradition, after all. But this was probably a good thing. Written documents were less reliable over such a vast passage of time. They are very easily doctored, mis-attributed, edited with additions and deletions,etc, by the editors who control their copy and circulation. Anyone involved in studying or translating carefully ancient texts runs into all of that very quickly.
With Buddhist texts what we have is a very large body of literature expressing a set of ideas in innumerable different ways. It doesn't lend itself very well to literalism of any kind. There will always be some variation found elsewhere that is different. Buddhists tried to avoid the "word of god" problem of other religions. They are more interested in what is true than in who said it originally. They assume everything the Buddha said was true, yes; but not that only what he said was true. So it was a more open canon than other religions.
This particular text is not part of the oral tradition originally. At least, it is not contained in the later written versions of the oral tradition that exist, such as the Theravadins' Nikayas or the Sarvastivadins' Agamas. It belongs to a genre of Buddhist literature that seems to have begun after writing was introduced and was part of the Mahayana movement that espoused the bodhisattva path.
Many of these texts have this kind of cosmic imagery you've found here. Some sound like candidates as the original science fiction. For example, they wrote about an infinite number of inhabited worlds in all directions from ours, which also had Buddhas. There was a literary device of having a disciple of a Buddha in some unimaginably faraway world hear about something happening on our world and coming to pay our Buddha a visit.
If you want to delve into the closest thing to the oral tradition that still exists in English, I would suggest checking into the translations of the Pali canon. It has been translated completely at least once, and now most of it has been re-translated into a more modern language. Wisdom Publications has been publishing the new translations.