Looked it up, "hu" apparently isn't a prefix and the words "human" and "man" are simply separate entirely and have (very) slightly different meanings.
Alright fine. I shouldn't have said anything about a prefix. Who is HU? What does it mean to be HU-man?
human (adj.)
mid-15c., humain, humaigne, "human," from Old French humain, umain (adj.) "of or belonging to man" (12c.), from Latin humanus "of man, human," also "humane, philanthropic, kind, gentle, polite; learned, refined, civilized." This is in part from PIE *(dh)ghomon-, literally "earthling, earthly being," as opposed to the gods (from root *dhghem- "earth"), but there is no settled explanation of the sound changes involved. Compare Hebrew adam "man," from adamah "ground." Cognate with Old Lithuanian žmuo (accusative žmuni) "man, male person."
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