I have no doubt that there was an itinerant preacher whose name is rendered Jesus in modern times. He was inspired with John the Baptist and his message and asked to be baptized by him. This is somewhat of an embarrassment to Christianity so the Gospels have developed various ways of explaining how Jesus was greater than John.
The gospels we're written some 30, 40, or 50 years after Jesus's death. I think the Jesus Seminar is helpful in summarizing what we actually know about Jesus. Although I have not read much by them, several authors have conveyed the gist of what they have found. While Jesus spent much of his ministry in rural areas, he finally brought his message to Jerusalem. His challenge to both the Jewish and Roman authorities got him crucified.
While many of his followers focused on his teaching, healing, and concern for the poor, others began to think of his life as a type of sacrifice. Jesus was a Jew and at his death all of his followers were Jewish. They searched the Scriptures and found the suffering servant. But there was a diversity of beliefs in early Christianity.
By the time the Gospels we're written, the Jews had been kicked out of the synagogue and Jerusalem and the temple had been destroyed. So the gospels have anti Semitic language. But as we know from Q, Jesus's ministry had an important element of the teaching and healing. He did not reject his Jewish heritage, he merely challenge the oppression of the peasants by the Jewish authorities and the authorities cooperation with the Roman domination.
The urban Christians were very dominant in writing the received story of Christ. While the role of women in supporting Jesus's ministry is obvious, the true extent and the names of many women are suppressed in the Gospels. And Paul who had never met Jesus before his crucifixion, put himself at the same level of knowledge as the disciples including Peter and James, Jesus's brother.
It is easy to argue that the documents found at Nag Hammadi are not as old as most of the New Testament documents but they reveal the diversity there was in Christianity that Archbishop Athanasius, following Bishop Irenaeus was very sucessfull in hiding. Rather than seeing books of the Bible as either in or out of the Canon, it makes more sense to see the entire New Testament as a continuum from fairly accurate to fantasy with none of the books being a eyewitness account.
So as I have mentioned before, I repeat Bishop Spong's declaration Jesus did not die for my sins. I understand the Gospel of Mark can be read this way. The empty tomb in Mark tells his disciples to go out into the world, don't worry about a dead body. Too much is made of a bodily resurrection by emphasizing certain descriptions in the Bible. The word resurrection does not appear, but it was clear that Christians felt Jesus had been raised to a special level by God. By the time the Gospel of John is written, Jesus has become one with God and they had to develop this odd theology of the triune God. In the beginning was the Word, and the Word was with God, and the Word was God.
Besides the anti-semetic and sexist problems that developed in Christianity, there is an emphasis on belief and magic. Emperor Constantine waited until the end of his life to be baptized which illustrates the feeling that something magic happens during certain rituals. During his life to help unify the empire, he got the Christian authorities to come up with orthodoxy. They did such a great job that it wasn't until the discovery of Nag Hammadi that the diversity was confirmed. Christianity also held onto ancient beliefs about homosexuality that are still with us today.