Remember the first Buddhist scriptures were not written until more than half a millenium after the Buddhas death.
And they came with the cultural legacy that surrounded all religious thought that emanated from ancient Bharat.
It was necessary to use certain concepts drawn from the mythos of the Sub- Continent.
That was the basic conceptual language needed for communication of things Dharmic.
So....a teacher whose birth was not seen as being miraculous in some way, and was not attended by Devas and associated with elephants and lotuses and so on had no chance of his teachings being taken seriously.
