How the f*uck do I find out what the third-person singular pronouns of ancient languages sounded like and what the f*uck do I do with sign languages
And perhaps easier for people here to answer: What are the gender-neutral or non-binary pronouns of your native languages? What are the histories of these pronouns? Even if it isn't a language of Europe it'd be interesting to hear about.
German was incidentally what inspired this project, because I had read here about various German neopronouns, of which the most interesting was hen (dat. hem gen. henser). German hen was loaned from Scandinavian hen, the first attestation of which was in Swedish in the 1960s when it was first proposed. Swedish in turn got hen from Finnish hän, which has always been a gender-neutral language. Hän itself originates as an irregular debuccalization (apparently a reduced form) of Proto-Finno-Ugric *sen from Proto-Uralic *se(n).
But German seems to have a lot of different pronouns currently competing for the top spot, another proposal is apparently loaning English they and "germanizing" it into dey (acc. demm, dat. denen, gen. derer; alternative inflections exist). There is also the sere-German proposal of using a portmanteau of sie and er, sier (acc. sien, dat. siem, gen. sieser; alternative inflections exist). And there are many many many other proposals.