Interesting premise here, which I won't debate, but just add it's not the only theory.
What I've pointed out is the common origin of mankinds beliefs about the Messiah as taught by Noah and the distortion of that concept. The only point being that we assume because some surviving record which might have been a distorted record, just because it's in an older extant copy, has more validity or predated a more original version of which we only have later copies. It's like the flood myth; each culture has it's own take on it but that suggests a common origin.
The issue of the Messiah could be the same. Genesis sets the premise for the Messiah being bruised in the heel by the Devil. If Noah understood that the Messiah would come and die for the sins of mankind then that's all the foundation you need for varying and evolving Messiah myths. Furthermore, sometimes myths grow out of strategic historical events and become mytholigized.
Now, as far as the NT is concerned, there is a little wrinkle. That wrinkle is the fact that the primary contributors to the NT, John and Paul, never died per critical Biblical understanding and as believed in certain "anointed" circles.
Jesus said that "some standing here would not die until he arrived"; and several references in the scriptures shows there were two recognized classes during Jesus' day; one which would die and then resurrected at Christ's return and another class that would not die at all. This was considered literal. John in the last verses of his book discuss about the rumor that he "would not die", but that was only in the conetxt that Peter had been told he would die and this simply addressed whether John would be in the "living" group or the "resurrection" group.
Of note, Paul includes himself in the group of those who would "survive until the Lord's day" in comparison to those who would die and get resurrected later at the time of Christ's presence: 1 Thess 4:15 "...WE THE LIVING who survive to the presence of the Lord shall in no way precede those who have fallen asleep in death." Note he is establishing two groups: the living who SURVIVE until the Lords presence adn those who must fall asleep in death. But he includes himself in the former group, when he says "WE THE LIVING." And he uses the right term, "survive" since he is talking about 1900 plus years! Of course, most persons cannot handle the idea of a group of original Christians living all this time.
Even so, there is a basis for this belief in scripture. But that being the case, certainly John and Paul were around to influence the NT canon, at least that's the presumption. So the usual presumptions would not in particular apply to the NT.
In addition, as I said, Noah would have known of the Messiah and his ransom sacrifice and that would have been sufficient common knowledge to explain the consistent myths about a dying god who rises later and gives life to all things. Only it got connected with spring and the land and other distortions. Even so, the Jewish belief in the Messiah needn't have been based on the pagan adaptations; their myth of the Messiah goes all the way back to the Garden of Eden.
But as someone else noted, when it comes to history and what we can actually PROVE, we can only get so close.
Nicely prepared article! I enjoyed reading it.
L.G.