Will racism ever end?

"Race" is extremely dubious a definition alright. Complex populations of peoples with broadly shared genetic heritage over time with some regional overlap fits better, though is a bit of a mouthful. 😁 Those populations would roughly align with the idea of "race", in that broadly speaking modern human populations can be labelled African, Asian or European. Darkness of skin would be a small part of it. The "European" label could apply to North African, Arab and Indian as well as Northern European. There are some indicators even in our bones. For example a pathologist if presented with an African, Asian or European skull would have a fair chance of narrowing down ancestry by that alone.

Our evolutionary history follows the same basic trends. Africa, that is East and Sub Saharan Africa has the highest genetic diversity on the planet as that's where Modern Humans first evolved, had the largest population and were around for the longest(circa 150-200,000 years), Asia and Europe would have lower diversity, as Modern Humans arrived there much later(circa 70,000 and 40,000 respectively). Two African blokes living a few miles apart could have more genetic diversity going on than a Swede and a Greek, or Korean and Japanese. We see similar in the genes of archaic humans we met(and shagged) along the way. Europeans have Neandertal admixture, Asians have Neandertal(different mix than Europeans) and Denisovan admixture(and possibly Erectus), Africans have neither, though do show evidence of their own ancestors getting jiggy with more local archaic populations.

'Racism' per se only came into play in the 1700s and 1800s with the onset of the slave trade, where Africans were dehumanised in the same way that Irish were dehumanised, so that the imperial powers of Europe could justify treating them like animals and sending them off on slave ships to America and elsewhere. Race and Racism is an invented concept.

Not quite and that's a very eurocentric/American viewpoint. As is the modern first thought when the word slavery is mentioned. We pretty much automatically associate that word with the Atlantic slave trade. Slavery has a far longer history and across the world than that horrible time and was just as likely to be Whites or Asians in the mix. In Greece and Rome slavery was part of the social fabric. Their societies couldn't function without the practice. In Rome many doctors were Greek slaves. In Sparta the enslaved Helots outnumbered free Spartans by about five to one. Never mind that in many African societies it was also a fact of life and remains so in a couple. White Europeans arriving to the Slave Coast(Nigeria/Benin/Cameroon) didn't bring something new. Quite the contrary. They were simply new customers for a long established and highly organised business. Even today there are people from that neck of the woods who would have had great grandfathers who were slavers(BBC link to one such I love how she justifies it. No way would she apply the same criteria to a European). The Arab trade in African(and European) slaves was also going long before and long after Europeans were in the mix.

As for racism itself? Well there has always been a Them Vs Us, belonging, not belonging trait in humanity and from the earliest writings we can see this. If the Other was a different colour, then all the easier to mark them out. Tutankhamun a north African/Southern European had among his funerary goods slippers which had images of Black African(Ethiopians/Kushites) on the soles so he could walk on them with each step. Egyptians knew of and illustrated many different "races" as they saw them and also had the broad notions of African, European and Asian. The Greeks and Romans had their barbarians. Those considered uncivilised, open to subjugation and slavery because they were essentially born to it. Most cultures did and in many ways do and it's why that word and concept has remained intact over the millennia. In many East Asian cultures going back into antiquity pale skin was lauded as a sought out positive over darker skin along class lines, just like it was in Europe. "Blue blooded" comes from the rich not having to toil outside remaining pale so you could see the veins through their alabaster skin. Shakespeare's Othello was written in the first years of the 17th century, before the Atlantic slave trade really took off and illustrates and considers the attitudes to the "Moor"*, the dark of skin, the Other.

So racism and prejudice towards the Other has always been around. Later European thought added a "scientific" angle to it in the midst of the Enlightenment and after, though there had always been some "explanations" brought to bear on the matter when seeking to excuse and dehumanise the other.

*Moor generally meant North African/Arab, rather than Black African and there is still debate over what Othello was in period, but he could have been anything non White and it would still make the same points.

Again I think that assuming idiocy in such things is problematic and over simplified and explains things far too easily. Many if not most of the greatest minds in human history have been prone to some "ism" or other, including racism. I'd say racism came second only to sexism. If so called cancel culture were to go down that list to expunge such people there would be remarkably few left on it. Looking over my own life I've met a few people who mightn't have been the sharpest axes in the toolshed but who were anything but racist, and on the other side of that coin some of the most intelligent people I've met were incredibly racist. If were only scumbags and thickos it wouldn't be the problem it is in societies.