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So no, we're not some essentially altruistic species that only survived to procreate and evolve due to our perfect selflessness.
did you miss?
Humans didn't go extinct, not because we're altruistic, but because we're self-interested. The post-WWII peace period (again, very relative), the UN, the rules-based-order, nuclear non-proliferation; there's about four reasons why we didn't go extinct in just the last century, and every single one of those reasons only happened because of nations engaging due to self-interest.
It's also too early to claim humans haven't wiped ourselves out yet, because so far it's looking like nothing is going to be done to stop climate change or AI from leading to our extinction, unless the oligarch-class decides it's in their self-interest to do something to stop it; or, ideally, concerned citizens acting in self-interest finally convince their political representative (who are also, by the way, acting in self-interest) to impose and enforce regulations to put a halt to that destruction.
Humans didn't survive the past several millennia since the dawn of settled civilizations because of altruism. All along the way, civilizations have been conquering, overthrowing, dominating, colonizing, and enslaving each other. They keep the local people alive (when they do) only out of self-interest, because slaves and serfs are more valuable to them than corpses.
Now, before you misattributed evil inclinations to me, I'm not saying there's anything morally right or good or just about that. But no honest reading of history will tell you anything to the contrary.