There is not one origin of Jesus story. It's a hero saving people story. It's the oldest story. It is not even the last one. It got a big break, because of the circumstances and the time it coincided; the culture it produced has been dictating the world.
There is no rationality or logic in dicussing what did he do or say and happening in the story and why. It's a series of parables in different levels. It doesn't make any sense.
The story of a svaiour man was made an official religion by an emperor in his death bed, because he was scared of slaves and soldiers believing in it in too great numbers. Later, the protagonist was turned into a god, and his mother into a virgin in a council, because all mythical heroship is based on being some sort of superhuman, god or being related to a god by family or a 'supernatural' circumstance fitting the order required.
You can't have a single mom sleeping around, or a human father, if you are going to make the son god. You can't have a human being walking around just talking to people, you need to make him do 'magical' things, so people would hear/listen about him, because men always talk to men. You can't kill sacrfice a man to save men, because men has always died for other men. You need to scarifice a god, so the me-me-me monkey will listen the story. (Commercial line; 'You deserve the best')
Nobody watches a 'man movie', where a Clark born to Kents walking-running around trying to save people as a rescue trooper. Doesn't sell. People want to watch a 'superman movie' where he flies. You wouldn't know it was made if it was 'man movie'. Audience was the same thousands of years ago. And before that and before that. Scripts were better and more benign though.
Exactly the same way, that's why at some point god got promoted to the creator of the universe, but not just the world. (Though I am not sure if the believers got promoted to get the difference.) Long before, it was just the forest or the mountain he created, it was the 'village', before that it was the fire in the cave...etc. That's also why we have Intelligent Design today. Adjustment.
There is not one origin to this story, it does not need an origin.