Even to this day in African slavery is almost entirely heritable, I'm using 'almost' completely as a weasel word - to my knowledge it is 100% heritable and is certainly a major cause of the perpetuation of slavery in Africa today. In your links there you'll find numerous contradictions. The second wiki leads with, "In general, slavery in Africa was not heritable – that is, the children of slaves were free – while in the Americas, children of slave mothers were considered born into slavery.". That is followed near immediately with the quote, "The slaves which are thus brought from the interior may be divided into two distinct classes – first, such as were slaves from their birth, having been born of enslaved mothers; secondly, such as were born free, but who afterwards, by whatever means, became slaves. Those of the first description are by far the most numerous....".

Similarly the first link tries to downplay chattel slavery at one claiming that "Precise evidence on slavery or the political and economic institutions of slavery before contact with the Arab or Atlantic slave trade is not available." And almost immediately following, "Chattel slavery had been legal and widespread throughout North Africa when the region was controlled by the Roman Empire (47 BC – ca. 500 AD). ... Chattel slavery persisted after the fall of the Roman empire in the largely Christian communities of the region. After the Islamic expansion into most of the region, the practices continued and eventually, the chattel form of slavery spread to major societies on the southern end of the Sahara (such as Mali, Songhai, and Ghana)."

Wiki does not tend to deal with issues that are contemporary, or involve social issues. And I think this is probably an instance of that. I think instinctively some want to demonize our actions so much as possible even if only as a sort of self flagellation. And so appealing a spin on the myth of a noble savage would certainly do as much. In reality we utilized, incentivized, and adopted an inhumane system, but it was not our direct creation in this case. And while we have learned from the past and moved on, these systems of inhumane exploitation which existed before us continue to exist without us.