Yeah it seems to.me that most of the in-game "lore" regarding magic is specifically set up to discourage critical thinking.
"It's all magic maaaann...you just gotta feel the Weaaaaavvee brooo. "
Personally, I'm not too stressed about classifying the magic and the nonmagic stuff (though I'd agree there are ambiguities there).
The bit I would like better explanations for is the mechanics of spellcasting, e.g.
--what's so special about the way that spellcasters deliver spell components that prevents non-casters from being able to do it?
--how is it that the only action that has no chance of user error is "casting a spell"?
--what makes one spell more difficult to cast than another (such that it cannot even be attempted at all until it can be executed with 100% effectivness), and how does that manifest in the fiction?
Stuff like this would (IMO) help casters feel more physically tethered to the worlds they dwell in rather than just having a growing list of game mechanics they can take advantage of with near zero fictional justification.