Andréa, Canis Lanonbinary

And this is just how pronouns happen in many languages! Spanish in particular started with the two second person pronouns from Latin, tu and vos, which started as a singular and plural pair, but turned into a informal/formal pair, and eventually in various dialects of Spanish one or the other is no longer used, and both are considered singular. We've so far gone from two to one pronouns lol, so what replaced them?

Well, a new formal pronoun was invented, usted, a contraction of vuestra merced, lit. "your grace". And that's why it uses the third person conjugations, grammatically it's still a third person noun. And there's also a plural of that, ustedes. And then there's vosotros in a few places, literally "you others" but spiritually it's just "y'all". And so we're now up to four second person pronouns in some regions lol.

And this is just the example I know, I'm vaguely aware that Japanese has a ton of pronouns, many of which are fairly recent, one set is specifically for the Emperor, others have fallen out of fashion, etc.

Last note: the tu/vos section above happened almost identically in English as well, with thou/you. Started single/plural, went informal/formal, eventually collapsed to one (most speakers chose "you" but the Quakers chose "thou" because they thought the formality was unnecessary among a Society of Friends), and then in a bit of a curveball, thou became archaic and so ended up even more formal than you for a short time, before eventually completely dying out in the modern language. Spanish just has enough regional independence in language that tu/vos survive to this day.