Old thread, but what the heck. The genealogies are different, I think, because they are inventions by different authors. Matthew traces the family line only back to Abraham, while Luke goes all the way back to Adam. Since both go through Joseph, who wasn't J's father anyway, both are bogus. I doubt that either one has anything to do with oral history, and in twenty years of study, I've never heard of this name skipping "tradition." The "mysteries" of the Bible go away when we think of it as literature arising primarily out of folklore and oral tradition, with occasional--though often garbled--historical and/or geographical correspondences. There was a city called Jericho, for example, but it didn't have walls in the time of Joshua, though it did when King Josiah's priests renovated the Temple and revised the OT, very likely writing Deuteronomy at the same time. Of course, Peter Pan begins in London, but that doesn't make Neverland real.
I don't think it's so much that they're taking the texts at face value, more they are trying to figure out what are the actual teachings of Jesus and what were later additions. Many argue that Jesus was real and there's a historical core to the texts, but that's about it. What can we really know about the historical Jesus from the texts? That's the question.
I don't doubt that there was an actual rabbi named Yeshua who may be the source of an oral tradition around which a new sect of Judaism coalesced in the first century, but there is very little about him to be found outside the Biblical canon and/or non-canonical Jewish and early Christian writings. Of course, illiteracy rates were at about 95% in the ancient Roman Empire, very little in way of education, and no mass media, not even print. Most people were ignorant and superstitious, believing in magic, visions, mysticism, etc. They probably would have had little trouble believing in miracle cures, the raising of the dead, turning staffs into snakes, flying, etc., and most of their information would have come from oral communications, perhaps little more than rumor. It's always puzzled me, for example, not that Jews believed that Moses could turn his staff into a snake, but also that the Pharaoh's magicians could do the same. That Simon Magus (Acts of the Apostles) could fly. There were eight or nine people resurrected in the Bible, and hundreds that supposedly climbed out of their graves and wandered the streets of Jerusalem at the moment of Jesus' death.
Was there a real Jesus? I don't know. Did he do the things his followers, the gospel writers that never even met him, later claimed he did? Of course not. Such things are impossible.