"Believe only what you yourself test and judge to be true."

Yes indeed! And then there will be a lot of stuff that you cannot test. As for that stuff, you will have to make the best guess you can about it, and accept that other people may see it differently.

My best guess is that Jesus, and Buddha, and Krisha, and many other such figures existed...meaning only this: they were real, physical people upon whose lives and reputations great religions were inspired and eventually established. Whether any particular thing said about any of them in those religions is half-true, all-true, or wholly false is simply a matter of speculation and guesswork at this point, and no amount of talking about it on this forum will prove any of it one way or another.