He may not have been a literal historical prince, but to make the distinction may be to miss the point a bit.
For example if you compare the Mesopotamian creation myth, the Enuma Elish to the book of genesis you will find many correspondences at the formal level.
What I mean by that is that the overall structure of the Enuma Elish is preserved in Genesis, but with some changes. In the Mesopotamian myth, there were seven generations of gods, but in Genesis this was transmuted into seven days for one god.
You could say that Genesis is a parody of the Enuma Elish. I don't believe for an instant that the people who wrote genesis believed in the seven days and what was created on each day, it's probably allegorical.
The most important point being made in genesis is to be found not in the sequence of events, but in the differences against the backdrop of the Mesopotamian myth, the main one being that there is only one god.
Likewise, the embellished life story of the Buddha, the bit with the white elephant, and the birth in a palace, and the journey on the cart through the town with the charioteer 'Channa' all borrow elements from well known Indian motifs. The most important parts of the story are probably to be found in the 'diffs' and are not to be taken literally.
They probably weren't even taken literally at the time.
In summary, I think we are reading too much into ancient texts that were probably written in the allegorical mode.