This is how I see it. Since the stories are like fairy tales and fables it follows that they were intended as the word Torah suggests to instruct children.
While they may seem like fairy tales and fables (because they are, being embarrassingly disconnected from reality), they were and still are taken as absolute fact.
Yes, I agree, what Moses was teaching was set aside and lost to time probably ever since Moses died. However there is some evidence that secret teaching was passed down to initiates but deliberately being held back from comprehension by foreigners and even ordinary Jews as can be seen in the dead sea scrolls as a rule in the manual of discipline:
Of religious discussion.
No one is to engage in discussion or disputation with men of ill repute; and in the company of froward men everyone is to abstain from talk about (keep hidden) the meaning of the Law [Torah].
This seems to be what Jesus was arguing about by saying,"No one lights a candle and then hides it under a bushel"
Thats why some said, "Where did he get this teaching? " not because it was so amazing but because it was supposed to be kept secret especially from those who the religious elite perceived as being unclean, froward, or unrepentant 'sinners' like Jesus...
Jesus said that it was revealed to him by God. They knew there was no other possible explanation. They knew his family, where he grew up, what he was doing..... being tempted by the devil in the wilderness while living among the wild beasts, in other words living in non jewish areas presumably doing what romans do, not praying to a spaghetti monster in some orthodox community or chanting in a Buddhist monastery