Basically it's the understanding that we're all in this together and we shouldn't mess things in some way for other people purely for our own benefit. Think of it as avoiding negative-sum situations. More formally:
an implicit agreement among the members of a society to cooperate for social benefits, for example by sacrificing some individual freedom for state protection. Theories of a social contract became popular in the 16th, 17th, and 18th centuries among theorists such as Thomas Hobbes, John Locke, and Jean-Jacques Rousseau, as a means of explaining the origin of government and the obligations of subjects.
We're talking about something much more fundamental than social norms you might call patriarchal or cis-/hetero-normative or anything like that. This is the kind of behavior that keeps you from getting punched. And most people are explicitly taught these behaviors as children, whether in pre-school / kindergarten or just by being around other children at all.
Surely we can identify much more important factors propping up the current social order.
You seem to refer to something else.
It's kind of like with sports. Both football and basketball are perfectly fine disciplines on their own, but the most fundamental rule of any game is that all players play by the same rulebook. You can't have a game if every player thinks they're playing a different sport.
Of course, you're not Hegel, and I'm definitely not Russel. So I'll just leave it at that :)
Which is why we don't have to reinvent civilization every generation, forever not leaving the caves.
> and is a concept loved only by those benefiting from the current order.
Which, under reflection, should be most people, as the alternatives available through abandoning civilized society are strictly worse.