It's somewhat odd that the article addresses slavery without mentioning that Mansa Musa owned many thousands of slaves and that slavery was prevalent in West and Central Africa during the Medieval, pre-Colonial period.
Side point, it's always funny to me how a lot of Westerns are hesitant to admit that African societies in Pre-Colonial times had history, science, culture, etc. just as any other society, but very eager to exclaim that they had slavery. It's also as if the existence of slavery does not require a certain type of social organization to have been already developed, which then they claim Africans didn't have.
This is perhaps a provocative point, but legal slavery has not existed in England for about 900 years. The rest of your points are an irrelevant and inaccurate response to my comment, so I won't address them.
Plantation implies slavery in the US, but not everywhere.
I can at least imagine people quibbling about "science"; clearly, once again, every human society that has ever existed in the past two million years has some sort of technological development that required some kind of empirical process of understanding of the world, but I can see why people might not consider that science.
I think people are usually more dismissive of people turning historical molehills into glorious mountains. There's whole industries and groups dedicated to doing this everywhere in the world, on a sliding scale of extremist claims, up to and including "our ancestors had lasers and nuclear weapons, as demonstrated by these descriptions in our religious texts", but naturally you see it more often in places that aren't known as meccas of scientific and technological development...usually for good reason (they weren't). Even neutral well-intentioned people often stretch known historical reality too far in an attempt to make people look better, but it's usually nationalist partisans.
These people (the partisans) would generally be better served making their locales better today than trying to convince everyone of a glorious past that likely didn't exist or has been highly exaggerated.
When discussing African nuances between, slave, peasant, peon, churl, sharecropper, whatever are discarded, and all are designated slaves. In Europe such nuances are emphasised, frankly this is probably done unconciously for egotistical reasons.
Also telling that my criticism in that regard was immediately downvoted.