If the people Jesus was speaking to already understood the first few chapters of Genesis as a narrative which explained how humanity was made in the image and likeness of God, then they would not have needed to be told, “Oh and by the way it’s not to be taken literally.”
People in every age understand scripture according to their own context. for instance slaves would understand Psalm 136 (By the Rivers of Babylon) in a very different way than we would today.
Also Jesus didn’t spell out every single thing. He made no comment on slavery for instance, or on whether women should learn to read and write or go to school. He didn’t mention child labour etc etc.
Jesus’s life was about His death and resurrection. The Passion, Death and Resurrection came before the New Testament. And the NT was written in light of His Death and Resurrection.
When Jesus referenced Noah it was to people who knew the story and understood the message he was making: Jesus is the New Ark of the New Covenant, and this is another pivotal moment in history.
If Jesus appeared today and referenced the Noah story we would understand what He was talking about, though we wouldn’t all believe the literalism of the story in the same way.
Lets look again at what your writing. Didn’t the people Jesus was speaking to already know the nature of Jehovah God? Didn’t they already know the Sabbath rules? Ah, but they thought they did. They had to be corrected on the long traditions they held about the Sabbath. He told them the Sabbath was made for man and not man for the Sabbath and went on to show the truth.
They had an OT belief that was wrong about God. The trinity is revealed in the OT, but they didn’t see it. Jesus corrected them. So, here are just two (and there are more) major concepts from the OT that the people
already knew but were wrong about. Now, Jesus goes into questions about sin, nature, death, heaven, hell, angels etc., and clarifies old perceptions but never once does He go to origins or the flood, which was a staple of belief, and give a new understanding of it.
The NT is just that, NEW, and demands a new understanding, but Jesus holds tight to Genesis and the the Ark, even going so far as to connecting those accounts to Himself!
The new Testament was written "in light of " change on all things that of course also includes the all important life, death and resurrection. The answer to our true origins would be just left aside? He would bother to get so complex as to telling them how He was God but leave out that we also had a different beginning. He was a truth teller, not a pacifier of the status quo.
