Have you seen Monty Python's The Life of Brian? We shouldn't be so trusting of ancient sources, especially when they were in the business of proselytizing. For all we know, Christianity could have started from a case of mistaken identity, as the movie posits. But the historicity question is beside the point because the synoptic gospels present us with the character of Jesus, and that character has certainly impacted history, whether he was historical or fictional/legendary.