What exactly is the standard in your mind for whether a historical figure existed?
Hard evidence has never been the standard for proof that a historical figure existed. Corroborating records are. It's great if you can find some hard evidence, but if that was the standard then most people in history wouldn't have any historical proof of their existence. And even when there is a corpse, we still rely on burial records to be certain that the corpse is who we think it is. Or if there are letters, we can't confirm they were written by the same person we think they were.
Like a third of the bible as well as several contemporary documents all point to the existence of a guy named something like Joshua (which we now translate as Jesus) who traveled around Palestine preaching and was crucified in around 33AD. There are plenty of historical figures who we mostly agree existed despite having approximately the same amount of proof as for Jesus.