The bible is full of contradictions to itself, in part because it was written by so many different people over time, but it is also a work of philosophy that is more open to interpretation that some things. Some things are unknowable but most are not because a fairly clear picture can be drawn from looking at a variety of things that point in a particular direction, so I don’t agree with this statement: “What trace of war or violence is likely to remain from such a distant past? It is an unknown.”
It’s not an unknown at all. There’s a whole Wikipedia entry about Neanderthal extinction that discusses it in detail. Some is theory but a lot is well-supported by things that we do know, and although violence is one theory, it is the least well-supported possibility. There are skeletal remains of Neanderthals, and they did have some tools that could have been used to kill hominids, but there is also no archeological evidence of any significant number of these that show the kinds of wounds that would have been suffered in such a case. They did cave art, but there is no cave art about warfare, even though in later times there is cave art depicting war.
I’m not meaning to be obstreperous but it makes me a bit crazed when someone says, “Well we just don’t know” about something that we actually know an awful lot about.