Yes, that is the nature of language. We don’t speak like Shakespeare anymore either, imagine that. Queer people was offensive 20 years ago because it was mostly used as a slur then by bigots. It’s not as offensive now because queer people reclaimed it and it is mostly used by them to refer to themselves. They have generally expressed that they are more comfortable with it because of that. “Coloured people” is still used mostly by racists, while “people of colour” is commonly used by non-white people to refer to themselves. In each example an important factor is how the group being referred to feels about a particular term. Most black people have made it pretty clear that they don’t like being called “coloured people”, especially not by white conservatives, but they generally don’t mind the term “people of colour”. So if you have to use one or the other, the one that you know they don’t like is probably not the safe bet.