Mildly new-ish, coined in 1990: https://en.wikipedia.org/wiki/Two-spirit

Nope. It's basically just a term used for trans/non-binary people in an indigenous community.

For example, We'wha: https://en.wikipedia.org/wiki/We'wha

The term "two spirit" is relatively new(1990s), but many tribes would have a term for basically "a man who lives as a woman" or vice versa.

The first documented evidence of it seems to go back 300 years, most likely it has existed hundreds, if not thousands, of years before that.

It really isn’t - it’s been a part of many Native (north&south) American cultures forever.

Narrator: it wasn't

How do you prove this?