Hey Phizzy....I have had a similar fascination with the JTB character.
About 20 years ago we used to discuss this stuff on this site. I stumbled across an original copy of "The Lost Book of the Nativity of John" by H. Schonfield, signed by him no less. Anyway, it opened a new way for reconstructing Christian origins. It was surmised by Schonfield that the nativity stories in Matt and Luke were, if not originally directed toward JTB then at least parallelled by him. Yes they ultimately were drawn from the OT but history seems to have forgotten how JTB inspired similar if not identical legends to those associated with "Jesus/Joshua".
Given the abundant evidence for a preChristian anthropomorphism of divine aspects/emanations/hypostases of God combined with popular belief that a "Joshua/Jesus" would return to defend Israel and the "Messiah son of Joseph" (one of the 4 craftsmen who was to reunify Israel) The Qumran texts, that demonstrate similar expectations, link the Essenes who many regard JTB as being from. IOW, all the ingredients are there. It might just be that we have in fact long known the historical Jesus, he was right in front of us.
Some years ago, again on this site, Leolaia remarked about how the death (by "Herod") and claims of resurrection of JTB find a larger typology in that of Jesus. More and more it appears the author of Mark was a brilliant fellow, he packaged some deeper spiritual concepts into a theatrical style narrative. The Christ was a hypostasis of God and his narrative drawn from typological usage of the OT and in more recent times JTB.