'One hero made it happen' is an easier story to tell.

The reality is almost never that it all came down to one particular hero.

But the simpler story is the one that gets shared!

It's easier to transmit, so it can be shared more easily and shows up and dominates compared to the more complex / nuanced / longer story.

Mimetic fitness is not "It's right" it's "is it right enough, and is it easy and enjoyable to transmit and receive?"

A story that "clicks" or "fits" in the receiver's brain (e.g. that confirms their priors, makes them feel smart for a thing they already believe) will get shared more often.

It will be over-represented, not because people did it on purpose, but that's just the edge on what things people bother sharing, and what kinds of things people tend to actually receive.

The result is that most stories are about heroes and yet very little value in the world that we see was created by heroes.