Lord of the Flies was written by a sad man who had problems with humanity. I didn't react that negatively when I first read it, but I also definitely soured with time.

Something interesting is that a real life lord of the Flies has happened. Spoiler: they don't kill each other, they delegated roles, took care of the injured, established food sources, keep a fire burning for more than a year, and eventually got rescued.

Human nature isn't merely brutish, pushing people to murder their neighbors because they just felt that way uwu, instead it's some combination of rational and tribal. We do good by our tribe, we want to be accepted by our tribe, and we often unfortunately define ourselves in opposition to others tribes, whether they be real tribes in prehistory or Xbox vs PS4. However, people don't murder people over their chosen console, they're rational enough to realize that's beyond stupid and meaningless. Children stuck on a island have enough rationality to realize half of them dying is less hands able to work on group projects, and that rationality transcends whatever base tribalism that might energe. The past 20000ish years of history has had people rationally define themselves in gradually bigger tribes, from village to city to religion to nation to supranational identities at different times and in different places. WW2 didn't solely happen because humans bad and tribal, it happened due to complicated ideological breakdowns of rationality (among other things of course, single causes don't result in world wars) that otherwise would've had the Germans and Japanese realize that prosocial cooperation with their hated groups would've had better outcomes for all.