Additional proof of what, exactly? It certainly adds additional cogency for these narratives to have been able to be written by the characters themselves, or at least recorded by their near term relatives. The uncanny accuracy of the cultural information from, say, the patriarchal era, unavailable otherwise to Moses writing hundreds of years later, is explicated by this view, for example. It’s a trivialization to make this a matter of risking being misunderstood. Stand and deliver. What studying have you done in this subject?
Just a small contribution by one rather eccentric scholar, e.g.