I agree that the "law of the jungle" trope seems like an oversimplification.
But the fact that cooperation was also present in pre-modern societies does not completely refute the point.
That's why they are talking about tribes, not just families or individuals.
I an not a professional historian or anthropoligist, but the scope and phenomenology of cooperation in ancient societies is not a question with a global, settled answer, as far as I'm concerned.
I'm currently reading this book:
https://www.amazon.de/R%C3%BCckblick-auf-die-Natur-Geschicht...
It deals with many of these topics, especially the transition from hunter-gatherer societies to agriculture.
It is more academically rigorous than the submission post, and it quotes other research.
Unfortunately, there are two flaws:
a) the author has transitioned to what we'd call a far-right activist prior to his suicide. He became known outside the scientific community due to his book "Finis Germania" (which I haven't read). But the book that I am reading was published much earlier, and well-received by the scientific community. The same goes for other works by him. He focused on the living conditions that allowed for a humanitarian mindset to even emerge, basically what humans do to provide the resources for living.
b) there seems to be no English translation