Irrespective of the chronology, I can readily imagine how such a philosophy might form in the mind of a human-being in his position in the world. His ideas were transcendent and novel yes, but I see them as needing to be no more than his own. The degree of intellect demonstrated by the great greek philosophers before his time reminds us of the potential that man had already attained. Jesus's own education could have equipped him with all the tools he would require for the tasks he set himself, aided of course by his intrinsic genius.
Simply by basing his appealing messages upon a set of irrefutable propositions he could pass them into the realms of apparent truths upon which the christian faith could attach itself. I'm not suggesting he was an out-and-out "con artist" except I do suggest he borrowed the methods in order to further an arguably just cause.
I suspect that many are readily attached to the Christian message because it appears to offer a set of attractive absolutes. Take for example the golden rule:
This typical (but non-exclusively) Christian message seems on the face of it to be a real nugget, but it turns out to be iron pyrites when your realise that it is at the mercy of ego. I have yet to see a single account in any religion of what I would consider to be a divinely inspired absolute delivered from beyond the realm of our own limited capacities.Matthew 7:1 wrote: All things whatsoever ye would that men should do to you, do ye so to them; for this is the law and the prophets