In Equestria, Part 3

Humans coined the word humane, naming one of our most important values after ourselves. The corresponding etymology for ponies yields chivalry.

Note that this is not the highest value, but rather the minimum. To call someone inhumane is very much like calling them inhuman: it is simultaneously an appeal ("like any human, you must know instinctively that this is wrong") and an accusation ("by doing such a thing, you behave like a monster rather than a person"). Likewise, then, chivalry would not be something ponies attribute to their greatest heroes, but rather something they expect of everypony.