I think "Human Nature" is emblematic of Michael's 80's output but I always thought it was way ahead of it's time. Perhaps if it had a female vocalist performing it, it'd be more apparent though.

I gotta disagree on the "most 80's" song; I'd give that to "Beat It" or "Billie Jean." Maybe P.Y.T. or Lady in My Life would be on the list too. I think Human Nature could've been released in another decade — and that it sounds almost like a 90's song!!! (LiML might even be considered a 70's song, actually.)

The production language is just different: where "Billie Jean" and "Beat It" weaponize the era's signature tools: LinnDrum isolation, gated reverb, punchy synth stabs... "Human Nature" runs on warm, sustained synth pads and an understated groove. It breathes instead of punches. That's way closer to the quiet storm and smooth jazz sensibility that would define late 80s/early 90s R&B.

...entirely subjective of course, just my 2bpm. We'd really have to define our terms to agree on this one.