But she ain't no human being is pretty clear.
I really don’t think you understand. Even at the time it was written it was understood to be exactly what he says now (anti monarch). I know, I was there. The pistols and many punk bands expressed the frustration among poorer youth in England who felt (somewhat legitimately) that they were doomed to wallow at the bottom of the social ladder with no way of getting out and upward. They looked at the monarchy as representative of a caste system in England where if you were born poor, you basically stayed poor.
“She ain’t no human being” is very clear and refers to the idea of kings and queens as being interchangeable and not a single person. If the queen had been Betsy Boop she still would have had as much power, wealth and influence as Elizabeth. The queen is the female monarch, always was and it did not matter what her name was, it was the title that mattered.