my viewpoint is that the human ability to cooperate effectively is why there's currently 8+ billion of us on earth and chimpanzees are an endangered species.

Our capacity for stories and language helps us create large cooperation networks, which is a unique evolutionary advantage.

Chimps have cooperation limited to "we are genetically close and you give me banana so I give you banana".

Humans can create something like the Roman Republic, or modern nation states and corporations, based on a shared set of stories and language (culture, also includes stuff like rituals, socio-sexual taboos, etc), which enables millions of us to collaborate together towards a common goal. Which is why we're so successful as a species.

Capitalism allows thousands of people who don't know eachother or even speak the same language to work together to make all the components of a pencil.

All of those people might be selfish, yet they still work together without even knowing they are doing so.