To get past the awkwardness of the uniqueness thing, I retroactively declare that we are looking for the unambiguously unique, physical, original object, which indeed in part represents a human, was created in a known year, etc. Clue: not many people have seen the original, and I can find no information about whether it even still exists.
Is it the photograph of the Tiananmen Square protestor and tanks?
Hail Radox! I note that the aforementioned Wikipedia has a "List of photographs considered the most important", though I'd think we're a few weeks away from recourse to that.