This raises an interesting question: why did the later idea supersede the original one? Presumably, because it was a better story. In fact, it must have been a much better story because no one bothered to preserve the original. This appears to create a problem when we try to understand the origin of Christianity. The challenge here is to understand what made the belief so attractive in the first place? From the mythicist perspective, the original belief was so unappealing that it was soon replaced by something completely different. This creates a fatal problem for mythicists. Mythicism makes the origin of Christianity inexplicable.
The answer to this is that religious conversion is driven by compensators, not by narrative. It's not the story, it's the promised pay-off. The original movement was almost certainly apocalyptic whether Jesus existed or not. The central belief was that Jesus was about to come back
imminently, not in some undefined, distant future, but within their own lifetimes. The social order would be reversed. The last would be first and the first would be last. The miserable (and it was miserable) existence of peasantry and slavery was about to be over and they would be given eternal life in glorified bodies (or whatever) while the rich pricks got tossed into the fire. That was the hook. The kingdom was at hand. It was going to happen any day now. There was no need for a story, they were just waiting for the Jesus and the angels.
When Jesus never materialized, expectations had to change and the compensators had to be modified. Rather than an imminent doomsday cult, it now became a personality cult devoted to the worship of Jesus, more direct focus on the person of Jesus led to curiosity about him, which led to searching the LXX and other literature to find perceived clues about him and ultimately to construct a "life" based on making pictures out of Old Testament clouds.
In short, there originally was no "story" or any need for a story, only the "good news" that the Anointed Savior was coming down to liberate Israel and sort everybody out. The need for a deeper narrative only arose as a result of delayed parousia.