that "law of the jungle" thing is a myth. people believe it because it makes sense, but it isn't real for humans or almost any animal species.
what really exists is that people feel very good when they view themselves as superior to others, and they come up with an insane amount of mental gymnastics to justify what they do to attain that feeling.
one of the great myths of nature is that predators have some sort of instinct to screw over their social group at every opportunity. even most animals know that there is strength in numbers and in fairness. we humans have taught ourselves that fairness and consideration of others are weaknesses and that feeling like a badass at the expense of others is very positive.
humans are literally an irredeemable species at this point, because all of the evidence of what I say is available to anyone with an internet connection, but it's easier and more fun to feel like a badass occasionally than it is to change your view of society, so the facts get ignored and humanity continues to destroy itself over smaller and smaller things.