Being a slave isn't human nature, but wanting to be a slave owner is. "Human nature" is, more often than not, a shorthand for "the parts of game theory that evolution distilled into humans"
(To be clear, not targeting you personally here, but targeting the rhetoric and fallacy)
If everyone else is defecting and you can cooperate with a few people, that's slightly better for you. Hence we have high-trust and low-trust societies, gatekeeping, etc.
If there's no pure play dominant strategy, you will always get a fraction of defectors willing to try their luck. But coopération still emerges, and the polities that manage to cooperate more still tend to survive and thrive more.