Jesus was made up after the fact to make the narrative fit the convenient needs of the new religion, but hints peek through. For example, He was most likely a disciple of John the Baptist until John was arrested, but later the narrative had to be warped to make Jesus more important. Jesus was not born in Bethlehem...Joseph likely was not from there.

Much of what we call Christianity was fabricated by St. Paul on the way to Damascus. St. Paul claimed to be another apostle, speaking directly to the late great Jesus, and concocted the whole "Jesus comes to save us from original sin" stuff. He got into vicious feuds with the real followers of Jesus, who hung out in the Temple trying to persuade other Jews about the Messiah. Fortunately for Paul, when the Jews rebelled in 71AD, the Temple cult was mostly massacred and since Paul had been preaching to large numbers of gentiles in the eastern Roman empire, his brand of Christianity survived. So Christianity is not even real "Christianity".

There's no doubt that the religion we now call "Christian" was primarily dreamed up wholesale by Paul/Saul and has less to do with the actual person of Jesus. Aslan makes some good points (and draws heavily on the "A Marginal Jew" series of books by a Jesuit priest). Jesus was a wandering prophet who likely learned under John the Baptist, who most likely was associated with the Essene cult that lived down the coast from where he did his baptisms...

Recall that Paul was the one who preached to gentiles, and eventually was forced into a deal by the temple cult that he would not try to corrupt Jews with his preachings. The real followers of Jesus were not interested in gentiles. Paul also wrangled the agreement that his followers did not also have to become Jewish, which demonstrated that the followers of Jesus did not care about gentile followers or consider them part of their sect