If you are looking for one word to replace he or she here it is, uou.
It’s not a new word. It’s been around for centuries and it’s been even used to refer not only to a person in either gender it’s also used to refer to God.
I’d like to suggest something else. Capitalized the second letter not the first. Like if we want to refer to God write uOu — or at the beginning of the sentence. Why? Because the way my mind works is non typical. It likes images more than rules and since English has rules and exceptions to the rules I don’t see why I can’t make that suggestion or the ones below.
His or Hers = uOs or Uos
Herself or Himself = uOself or Uoself
She/He = uOu