Anecdotally, my 70-year-old father and several of my elderly uncles & aunts had a much easier time figuring out Classic Mac OS. Modern macOS and iOS are much more complicated. While they still use these systems, they do so in a much more superficial way and they tend to exhibit what (for lack of a better term) I would call a "fear response." That is, when attempting to do a novel task they refuse to experiment and instead resort to asking for help immediately. Classic Mac OS was much better designed to encourage experimentation and avoided surprising the user (in a negative way) as much as possible.