Fieari
Explorer
Heck, even in Jack Vance's Dying Earth they at least had the concept of "Lesser" and "Greater" spells. Yes D&D wizards know what spell levels are.
Hitpoints, not so much. Maybe, JUST MAYBE, some weird mad philosopher-cleric might have studied hit points, but it's a vague philosophical concept that people just don't have any truck with. People think in terms of fuzzy logic and degrees instead of fine bright-line distinctions. "I'm hurt!" not "I'm down to 10% of my hp!"
Hitpoints, not so much. Maybe, JUST MAYBE, some weird mad philosopher-cleric might have studied hit points, but it's a vague philosophical concept that people just don't have any truck with. People think in terms of fuzzy logic and degrees instead of fine bright-line distinctions. "I'm hurt!" not "I'm down to 10% of my hp!"