

What do you mean? Almost everyone wants more, and will gladly take it if they have an opportunity. That’s why lotteries exist, right?
Big history is full of open questions, but there’s counterexamples. Short-lived republics are a dime a dozen, but Egypt lasted for thousands of years. There are known cases where inequality actually increases with the end of an empire, like how Roman Britain with it’s public bathhouses directly gives way to dark ages Britain with feudal lords and manors. In some cases, a disenfranchised group getting a bit of power is destabilising.
Tribalism is ancient for sure. As is cultural bigotry. Hating people primarily do to skin colour and related features is a thing that specifically developed 1500-1700, as the trans-Atlantic slave trade got going (and needed to be rationalised).
When the Romans or Mesopotamians hated on their neighbors, it was over food preferences, language and customs. If they ascribed anything biological to it, the prevailing theory was more about response to the local climate than heredity. Then, once monotheism got going deviation from religious orthodoxy became the most popular way to hate. It’s not a coincidence that “Slav” and “slave” sound similar, because pagan Slavic people were a major source of slave labour in medieval Europe. It drove the crusades, and it had a role in the early stages of expansion into the new world.
The first slave ship came to English North America in 1619, but the passengers were treated as normal indentures, and at least some became free later on. They kept coming, though, and by 1700 or so black people had to be slaves and that was pretty much it. (Colonial Spain had their own, somewhat divergent system a bit earlier)
The Romans had emperors drawn from Africa and the Middle East, and had conflict with Germanic and Celtic people that could easily have been Latin by appearance. The first sub-Saharan African in Japan was made a Samurai, and now there’s a videogame about it. That’s not to say the difference in appearance wasn’t noticed or remarked upon (they tried to wash the dark off of Yasuke, and Heterodotus makes special note of the woolly hair and stature of the distant Africans) but in every pre-modern story I can think of it was gotten over quickly compared to other, behavioral things.
Anyway, I guess the point is just that there’s been steps backwards as well. There would have to be, otherwise ignorance would have gone extinct over the millennia, right? Maybe it still will, we live in a totally transformed world now, but it’s going to require continuous effort. It’s always shifting and changing and evolving from things that might have started off as harmless or positive.