but then they got colonized by one of the most brutal, violent cultures in the world at the time.

The past is filled with cultures which commit genocide, mass mutilations, torture, systemic rape, etc. The Europeans are only notable because they had unusual success, because that success came at the same time as philosophical development which began to make that treatment towards other Europeans taboo, and because that success eventually was leveraged into a system of strict hereditary privilege we're still dealing with today.

The Europeans were not more torture-happy than the Natchez, not more murderous than the Aztecs, not more mutilatory than the Sioux.

What the Europeans were was hypocrites. At a time when humanist notions of basic dignity and universal brotherhood were being preached by scholars and theologians, European soldiers were murdering and enslaving Mesoamerican peoples en masse. In an era when tolerance was quickly becoming the watchword of the day, European priests burned ancient texts in the Americas for the suspicion of pagan notions. In an era when 'all men are created equal', American colonists denied not only the right of the Native American tribes to be equal polities, but even denied them the ability to be equal citizens.

It's less jarring when a culture which believes that incorrect ritualism will doom the universe murders people for religious reasons, or when a culture admits that it finds the murder of women and children to be an honorable deed to slay civilians, or that a chauvinistic culture extols itself above all inferiors; compared to one that preaches one value and acts according to another entirely. Not even in a selfish manner, but in a manner suggesting a total reversal of their claimed principles.

When American colonists murdered American tribes from the youngest to the oldest, saying 'nits make lice', that was not some exceptional deed that had never happened before in the history of the world; a scant few generations ago Europeans were doing just that to one another; American tribes had done the same to each other since times immemorial; same with every other suitably wide collection of cultures on the planet. The difference was that we were supposedly 'civilized' enough to recognize the basic dignity of one color of our fellow man, but none of the others.

THAT is what makes European colonialism repulsive beyond the 'normal' passage of history, the butchering of Saxons by Franks, or of Pawnee by Sioux, or of Chinese by Mongols. We claimed to know better - we demonstrated an understanding of the values that should have prevented such action - we demonstrated the ability to restrain ourselves in dealings with fierce (European) foes - and yet we proceeded to indulge in the worst impulses of man that we claimed we had left behind anyway. We were not ignorant, we were not running on fundamentally different values that made murder somehow okay like Bronze Age fanatics - we made a deliberate choice to exclude subsections of our fellow man from the 'enlightened' values we were redefining our civilizations by.

They were not medieval peasants who knew no higher word than their lord's. They were not Aztec warriors brought up in a culture of human sacrifice and flower wars. They were men who were raised reading the works of the humanist enlightenment, whose norms should have excluded many of the actions they took - but when they saw a human being of a different color than them, they turned every last goddamn one of those norms on its head like they were the Hebrews bashing in the skulls of gentile infants in the Bronze Age.