Earlier quoted context omitted.
> I'm sure I've run into other Chinese characters that are pronounced differently depending on whether they're in a verb or an adjective. The Japanese writing situation is much, much worse than that. Kanji get all kinds of different pronunciations on the theory that the semantics are the same. So the standard spelling of musume ["daughter"; "girl"] is 娘, but it might also be spelled 女. This gives you an alternative t…
> I'm not sure what a "moderate amount of Mandarin" means; if it's on the lower end, you might be interested to know that the "other" sense does survive in Mandarin, in the words 其他 ["other"; extremely common] and 他人 ["other people"; not so common]. 他 by itself is going to be overwhelmed by the far more common use as a pronoun, I would guess. I had a snippet about how 他 was made up of 也 and 人, "also a person", but en…
Well, I don't think it's true, either. As I understand it, the form 他 is just a graphical simplification of 佗, with no connection to the character 也. (You can think of this as similar to how the left-hand component in 脸 is 肉, not 月.) It isn't clear to me either that the character 也 would have held any sense of "also" when the form 他 appeared, though this is a question I'm agnostic on.
I've watched several videos on youtube in which someone presents Japanese people with uncommon kanji and asks them to read them, or failing that to speculate on what they might say. The Japanese unfailingly speculate that both halves of a compound character are relevant to the meaning, which surprises me - it's very rare for a character to be constructed from two meaningful parts. Far more common are the characters in which one part gestures at the meaning and the other part tells you the pronunciation, and 佗 is one of those. 从人它聲。