I think he didn't exist. Evidence?
1- his name. Why was it not Joshua? That is the usual transliteration of the Hebrew equivalent. A theory suggests that is was a subtle marriage of the Jewish god Jah with the pagan god Zeus.
2- When did he say what? Matthew and Luke quote Jesus saying the same things but under different circumstances. The reason for this is theorised to be that they both had a list of sayings, but not the narrative context, so they made different stories to fit the sayings.
3- Paul makes no reference to his ministry on earth. No miracles, no parables, no quotes- apart from more happiness in giving and the Eucharist. But surely he could have quoted more?
4- similarities with pagan myths. Suggests mystical origins for his narrative
5- No reliable secular references. Josephus' often cited references are plausibly fake additions. Odd considering God could have made sure there was plenty of contemporary writings to confirm his existence for later days.
It all adds up to a King Arthur type of historical character. He wasn't there but was a later amalgamation by people with an agenda.