That logic applies as well to minerals and fossils as to inventions. If I stumble upon a lump of gold, how can I own it? After all, it was merely “out there” to find.

Also, the question whether math is discovered or invented is an old one, with arguments going either way. It’s not like people just stumble upon certain proofs, or that Newton was just lucky.

https://en.wikipedia.org/wiki/Philosophy_of_mathematics#Math..., for example, holds that math would still exist if there were no life anywhere in the universe (maybe even if there were no universe)