Ours is a critical time in the cultural evolution of humanity that is likely to shape our long-term future, or lack thereof. As a species, we have been on
Effectively be definition, society is altruistic. It can't exist if everyone is perfectly selfish. There needed to be a balancing act between selfishness and selflessness, including some mixture such as "selfish altruism." Help me I help you. That's quite possibly the basis of civilization in general.
That being said, as beings subject to natural selection as well as self preservation and wants, we are generally selfish by nature. Whether we can override that or not depends on both our nature and our nurture. We did so far enough to form communities and eventually civilizations, of course.
If you want a detailed look on the topic, there's "The Dawn of Everything: A New History of Humanity", a book by Graeber and Wengrow, which also talks about the huge diversity of social models in old communities of humans.
I’m not convinced by any mass society that is altruistic, but it’s very simple to see that the natural state of human small groups is quite communal.
What mother has a ledger for the child’s share of food?
We have an entire feeling brain that’s dedicated to relationship building that’s very much the core of most small group relationships.
I’m also very convinced that this model does not work past Dunbar’s Number (~100-150 individuals), and most attempts at building communal society outside of that without some cohersion and some better way of organizing incentives is not possible.