As a counterpoint, if they hadn’t done it, someone else would very likely have done it. Individual artworks would be a more unique legacy.

Exactly. Inventions, knowledge, and other things are all inevitable--rediscovered and recreated from scratch each time. Art is our only unique contribution/feedback to the universe.

If you subscribe to determinism, all art pieces are also inevitable.

Quite clearly if population bottleneck wasn't dealt with noone else would be left to do it.

Sure, someone else would have overcome it. Could have been just around the corner. You don't know.

> overcame population bottlenecks

Their names were Fritz Haber and Carl Bosch.

Was more thinking about the Toba eruption bottleneck 75k years back, but sure :)