there arent any definitive answers to these questions, and answers that do exist arent easily accepted by all. selfishness comes from survival instincts, but otoh humans/primates are an inherently social species. theres no way to reconcile the two in a logical way as the premise/core assumptions you have are what define what answers work for you
socializing feels like an evolutionary means to an end and not as much about selfishness. for example, biologists organize to provide crutches to the damaged environment, clean up, plant new trees, etc. its a social activity that also involves socializing with other species of animals, through studying their environment, providing medical assistance. the process still causes indirect damage since all the materials used (metal, wood, electronics) involve ecological damage or child labor.
on the flipside, people can also socialize and organize into poaching parties and decimate whole species, murdering and driving them to extinction. the profits they make off their meat/hide/tusks helps the poachers feed themselves and their families and provide some selflessness or positivity as a means to and end.
its true that the way you perceive and define morals greatly changes the answer, making it super difficult. the answer i try to find in general is if the give-and-take nature of organic life is specific to the planet or is the best available strategy for survival in the universe.
i reject the assumption that humans are selfish by nature, i feel like the only way we survived in nature is through collectively helping each other out
cavemen grouped into tribes and would outsmart and outrun prey, its literally the only way we weren't torn to shreds by every animal
i see it as collective selfishness. the cells and organs of a Flash Mober have evolved to work together to sustain itself, and they will enable the Flash Mob to commit atrocities with indifference as long as they are fed. in the end, the cells get all the energy and oxygen they want, and the murderer gets a vessel to harm others. our ancestors could collect and organize to hunt, build and survive more efficiently than the rest, and the ones that died at their feet enabled their success. countries at war have millions of citizens collectively working for their own self interest and their own survival. whether they approve or disapprove of their government's atrocities is irrelevant because they will still work to eat, pay rent and taxes and enable the war.
it feels like the only selfless thing to do is die/go extinct so you can free up resources for other creatures.
