Ages ago, I found this blog post I found helpful:
Gender Neutral/Queer Titles
This is actually super important in a way I'm not sure people truly grasp: There have -always- been gender-neutral ways to refer to pretty much everyone at every tier of society. (Except in Latin, which did it's best to gender every single noun and pronoun)
Your Majesty is how one addresses a King or Queen, certainly. But there's a difference for the Majesty's kids:
Your Highness: Any child of Royalty who is not next in line to the throne.
Your Royal Highness: Any child of Royalty who is the Heir to the throne.
Heir, itself, is a gender-neutral term.
Why do we have this kind of specialized neutral term..? Why not have specific terms for Princess who is Heir to the throne? And the answer is:
Because it's just easier. By having a singular term applied to a child of any gender (Like the world "Child") you can refer to any individual who fits that category with the term. So why do we have the term Princess?
Because Latin was awful at literally everything and French is right behind.
Priisemokaps was a proto-italian word for "First Chief" or essentially the most important chief. What we'd think of today as basically a King. Over time, as Latin evolved it became Prī̆nceps (Pronounced Prin-Cheps with a soft i sound like in the word it). It's also why "Prī̆nceps Infernorum" is in the song
Personet Hodie even though people think of the referenced character as a king rather than a prince.
But you need another word for First Girl Chief because while Latin has no Articles and 400 different words for "Death" they always -had- to slap a gender on every bleeding noun they could. So some jerknugget said "Prī̆ncipissa!" and everyone cheered. (Meanwhile Heres remained shockingly gender-neutral and developed into Heir in secret)
But then came Germans. Isn't it always the Germans in etymology? And they introduced -their- terms for King and Queen and suddenly the world is in an uproar! The French had only recently "Fixed" Prī̆ncipissa by changing it to Princesse and making Prī̆nceps into Prince. What to do with these lovely words that would otherwise be consumed by the linguistic dominance of German?
Easy. Drop it down a tier.
And that's why we even HAVE words for Prince and Princess.
Etymology is grand, yeah?