This veils the nature of the Religion with No Name
Interesting (in a particularly challenging way for Catholic me)
I wonder to what extent this analysis would survive extension to apocryphal gospels, which seem like a natural place to cross-check any sort of "conspiracy" theory
Have you read On the Historicity of Jesus (https://www.amazon.com/Historicity-Jesus-Might-Reason-Doubt/dp/1909697494/)? You might get a lot out of this work, which attempts to test the question in a Bayesian framework and goes into great detail on various textual evidence.
I don't think denying the existence of Jesus as a human being adds much to that theory's cohesion. It makes more sense to me for Jesus to be a real minor religious leader. He foresaw the inevitable results of a clash between Jewish messiah complex and Roman might. He warned his followers enough to escape it both bodily and in belief, in the speech in Matthew 24:15-27: note the immediate switch from "Romans will crush you" to "don't believe in false messiahs". For that and several other acts of faith, notably going willingly to his own execution to keep his disciples from harm, he was venerated. When his prophecy came to pass in 70 AD, his cult was one of the best-prepared for the diaspora that followed.
My money is on him being Essene, inheriting the role of Teacher of Righteousness from John the Baptist. That, however, is a much longer thing that's only tangentially related, save to further argue that his beliefs are of Jewish origin rather than crypto-Greek.