All of these phenomena are completely predictable variants in the Neaderthal experience, as they survived for tens of thousands of years and lived through a lot of change. I don't mean that their physical world was unchanging, I mean their mental image of the world was unchanging. All their experience with everyday fluctuations of their living conditions, never brought about a change in their way of being, nor did they seek progress. In essence, they lived in a predictable world.
I would put it this way: They lived predictably in an unpredictable world.
That may explain why they aren't around any more.