There was probably no such person as Plato. There was a school. Before you say he had a history, a wealthy Athenian family, all that, remember they had the same kind of history for Theseus. At least they had a ship, or they say they did, for Theseus.
Dream on, kiddo.
The existence of a real person by the name of Plato, living at the time alleged for him, is amply attested to by an enormous body of work produced over a very long and very productive lifetime, in which certain themes ever recur, seeking ever better theoretical solutions, which the writer had the modesty to propose as "myths."
Myth gets a bad rap these days. Yet I think Eric Voegelin was entirely correct to say that "the myth remains the legitimate expression of the fundamental movements of the soul" (Order and History, Vol III, 1956.)
I think this is what Plato actually had in mind, in his work; which is why he did not leave us with a "systematic philosophy"; but only with the openness of mythical language.
Plus the other thing one notices about this magnificent corpus is that it is the creation of a world-class literary artist.
All in all, I think it is indisputable that this lifetime's work was effectuated by a single unified personality, who went by the name of Plato. And he had enough friends around in his day to attest to the actuality of his personal existence.
But then, you alreay know all that, don't you, RW? I think you're just "funning me!"