Jim Davila mentioned my article about the Rank-Raglan hero archetype and the historical Jesus. Jim notes that, if one includes all the Synoptic Gospels, then Jesus can be ranked higher than I suggested. When I referred to our very earliest sources, I had in mind the letters of Paul and the Gospel of Mark, which lack many of the details that are found on the Rank-Raglan scale.
Of related interest, it might be worth comparing Jesus mythicism with what one could call Homer mythicism. In the case of the latter, there is a huge difference in the evidence, and the time between the alleged era in which Homer is supposed to have lived and the first sources to mention him. But there are still interesting parallels in the arguments, including the highlighting of parallels with earlier and more widespread stories, as though any historical figure, or their teaching or compositions, ought not to reflect their cultural heritage.