The idea that humans are inherently selfish and work for themselves is one the most stupid fucking myths invented by capitalists, it's not even true in capitalism itself.
For all the individuality and selfishness that capitalism instills us with in order to survive in a cannibalistic system like it, you still see people going above and beyond and helping others with nothing to gain. Simple people risking their lives and swimming to rescue refugees so they won't drown in the sea, people making food and distributing it to the ones who need it, people who risk their lives to fight fires that the capitalist state is unwilling to do so effectively.
We are a species that started out by being communal and evolved that way, the very reason that we became so advanced is that we are so capable of communicating and coming together to achieve common goals. While it doesn't look that way in the capitalist dystopia that we live in, our nature is still inherent to us and it will awaken in full once we get rid of systems that rely on exploitation.