Same etymon as 仁 (OC *njin, “to be kind; to be good”), from Proto-Sino-Tibetan*s/k-niŋ(“heart; brain; mind”). The semantic association of 仁 with 人 was somewhat late, dated to Mencius's time; later on, 仁 would be usually interpreted as "humane, acting like a human being".
If so, semantically parallel with Tibetanསེམས་ཅན (sems can, “living being, human, animal”, literally “possessor of mind”); and Latinanimalis (“living, having soul”) from anima (“soul”).
From Middle Chinese人 (MC ȵiɪn). The 呉音(goon, literally “Wusound”), so likely the earlier or initial borrowing from Middle Chinese. (This etymology is missing or incomplete. Please add to it, or discuss it at the Etymology scriptorium. Particularly: “Explain nasal basis for goon reading/borrowing”)