Have done a lot of “parallel invention” where I invent something genuinely novel & new-to-me, only to later discover it was first developed eighty years ago.

The part that’s really disheartening is there’s so much knowledge out there, I wonder if this is actually efficient - maybe you can’t reasonably search the state of the art across all of human knowledge and so you have to invent it again. But that’s such a sad outcome.