Kind of a bad example, because mankind very clearly stems from 'humankind'. And people are lazy and prefer using short words. The unfairness is rather that women got stuck with the words requiring more characters. But that is a phenomenon of the English language and not present in others.

However, in most languages the words for man/male are closer to human(kind) than female/woman, which very clearly shows the historic patriarchal influence, coming back around to your point after all.

[–] CallumWells@lemmy.ml 3 points 10 months ago

Interestingly enough, in old English you had "werman" and "wifman" for man and woman respectively, in which case referring to all with "mankind" makes perfect sense. So the originator for mankind seems more likely to be from that than the explanation that it's a shortening of "humankind" to me.