There's many ancient religions that have that theme Fringe Dweller. Birth, Death and Reborn again. Modern day Wiccans carry it on with the moon phases. The Maiden, The Mother and The Crone, who dies only to rise again renewed at the next showing of the crescent (New) Moon. Its probably where the beliefs that have reincarnation of the soul as part of the cycle took the inspiration from. Why not, would you expect a child to learn all of human knowledge in a single semester at school.
But, to get back to the original question. There's no doubt Jesus existed, but as said before, was he, who knows
Bill