Gotta think of the Christian element too. Non christian peoples were considered 'savage' and not civilized. Makes dehumanizing a whole race easier. Did it to the Natives who were already here, brought us and did it to us too. Needed a way to justify the horrors and genocides. The thefts. How does one justify owning humans? Call us animals. How do they justify genocide? Dehumanize people and pretend they are not 'real people', just a lower species. Plus greed.
Easy to get the poor to go along with it if they are told that they are 'better' in some way and it gives them some status and power over the oppressed. They can always say 'at least I'm not a---'.

Sometime in the 1400's who stated all non Christians were worthy of being slaves. Chilling when you think of the Spanish Inquisition starting in 1480.

Global terrorism

Are you asking from the implementation of Chattel Slavery? The timelines show that it always existed in Europe - but it had shifted by the late middle ages - and brown skinned slaves came into Europe prior to 1492.

Those from what was called Britannia were considered so stupid they could not be good slave stock, according to Cicero. However, where there is money to be made, facts will be whittled or cut down.

Outside the questionably sort-of-European Ottoman Empire, wholesale slavery was dying out in Europe before the Triangular trade (plenty of serfdom and indentured servitude, but not the property from birth slavery.) I'm not really sure it was racism in the modern sense that moved slavery in the Caribbean from aboriginal peoples to Africans. Everything I've read just describes this as being a practical matter in that whites couldn't physically handle the work in that heat and the Caribbean aboriginal tribes were too intractable. Africans on the other hand could stand the conditions and, once ruthlessly enslaved and subdued, were less likely to revolt than native Caribbeans. That made this incredibly lucrative trade possible, so hello African slavery. From this in the late 16th Century it seemed racism was not born, but became much more ingrained and exacerbated, so it's quite likely racism as we know it became part of the white psyche because Africans were effective slaves. Prior to this practical shift, what racism seemed to exist was of the physical caricature type (Shakespeare's "thick-lipped Moor" and all that) which, while certainly unacceptable today, was not the subhuman idea of blacks that came after. Romans for example mentioned race very little. They were Emperors from Africa, and St. Augustine was at least half Berber (and this was before the Islamic Arab invasion.) It's telling that even though he thought of himself as Berber and African, there really is no concrete proof of his skin tone, because it wasn't all that important to him and those around him even in Rome or Milan. All the evidence suggests while he would not have resembled a Masai in skin tone, he wasn't exactly an Aryan either. Nobody seems to have cared enough to mention it in hundreds of writings by, for and against him though.

Once American slavery took hold, it lasted longer than just about anywhere certainly in the developed world in great part because of the racism that deemed blacks inferior and animalistic. Apologists (and to be fair, serious historians) will often point out that there was white slavery of a sort in the Americas, but it was neither of the same kind, or duration, or extent, as black slavery, and hopefully nobody needs to be convinced that the centuries of black slavery in the US followed by Jim Crow followed by sub rosa white supremacy movements have deeply inculcated racism that persists today.

But there are writings from slavers that explicitly talked about how solidarity between oppressed black and white workers literally kept them up at night. Once black/white rebellions got going, they created a FLURRY of laws and social mores to keep that from happening, all within like a 20 year period. Miscegenation laws date from that period, and didn't just refer to marrying/having children interracially but even communicating, drinking together, going to church together, everything.

The reason I'm a socialist is *because* of capitalism's role in creating, institutionalizing and exporting (people forget this part) racism. Prior to the capitalist period, racism was more along the lines of xenophobia which unfortunately is somewhat endemic to the human species, but capitalism in the Americas made it a SYSTEM, along the lines of the Indian caste system.

With that said, American racism evolved to a point where the system persisted and has even tried to recreate slavery (sharecropping, Jim Crow segregation, private prison labor) in many forms, despite the original slave system being destroyed.