Even in modern society, 'Jesuses' are popping up like whack-a-moles. People who think they are the reincarnation of the original. I'm inclined towards thinking that such a man did exist but, as others have said, he was an amalgamation of many. There was something on QI about Christians hijacking a pagan tradition of 'Mithras', which became Christmas. Similarly, it grew around a man who was said to be born of a virgin and who became divine in some way. Similarly with Easter ('Oestre'- something to do with eggs and fertility).
I was raised a Catholic and did buy into much of it all for many years until I learned more about the (very deep) flaws in the Catholic religion as an institution. I've since abandoned all that but would still say I had 'faith'. My partner, also raised Catholic but now atheist asked me, recently, how I could have 'faith' if I no longer believe in much of what I was taught. I tried to explain that I just entrust myself to 'whatever'- faith in fate, so to speak. If there is some kind of divine entity, I'll be judged on how I live my life and the good things that I try to do. I try to keep it simple. I don't feel the need to do endless rituals to secure a place in some afterlife. Goodness, kindness and awareness of my (multiple) faults are the basic tenets of my 'faith'. If there is some kind of afterlife, it might count for something. I do try to keep some of the Christian values, just because I'd rather tune in to the better side of human nature than the worst. If there isn't an afterlife, so be it.
Cynics would say I'm 'hedging my bets', lol!