Another view, still based on narrative theory, is that we all love a good story. It doesn't matter how its presented to us. Today its likely to be a film or TV version. But in times past, they were usually oral stories told by a travelling teller or whoever,
Stories got passed around, and re-told and incorporated into other stories. See if you can think of another version of this story, which I'm re-telling in bits because i havn't got time to type it all out
"The Lord of Heaven above impregnated the daughter of the Lord of the Waters below, and a son was miraculously born, But an evil king killed the prince's father ... and the orphaned prince was cast into the wilderness at birth. There, instead of harming him, the wild beasts took care of him. ..."
That story came from Central Asia. But its possible to find elements of the story from other cultures. We cannot prove that they were borrowed elements or merely reflecting individual hopes and dreams. But if the cultures are in close contact with each other, as say the Israelites, the Egyptians and the Greeks of Asia minor, then we may suspect that borrowing of elements for stories took place.
The David/Jonathon story for instance seems to reflect elements of a story from the Iliad in Hellenic culture that tells of the 'love' between Achilles and Patroclus
And that is a well-known love story that was likely told and re-told by travelling story tellers as they travelled up and down the eastern coast of the Mediterranean.