But humanoids DON'T USE THE PC RULES. You said it yourself that they use NPC classes, or the shaman class (again, something that is referenced like what, once in the entire body of AD&D and never actually used in play) and they can break the PC rules whenever they feel like it.
One last thing for clarification since you seem to be misrepresenting what I said. When I said they were NPC classes, that means they were designed to be used as NPCs, not by the players themselves (that didn't stop people from playing them though). That does
not mean they use different rules than PC classes. They are literally built on the same ruleset as every other PC class. That's not contradicting myself.
Secondly, it is absolutely false (and pretty ridiculous) to claim that humanoids given class levels for shamans or witch doctors only appeared once in the entire body of AD&D. They are literally given PC class levels, and guess what? DMs used the PC class rules to run those NPCs.
If she's 16 hit dice, then why is she only a 14th level MU? That's not right. That doesn't follow the PC rules.
But hey, keep feeling free to take cheap shots pretending I don't know the game. After all, you've repeatedly contradicted yourself. I don't really have to do anything.
If you have to keep quoting the same post multiple times, I think you probably need to step back and take a breather. I'm not taking cheap shots, I'm pointing out how you seem to claim a position of authority here based on your experience, and yet I have to explain basic 1e concepts to you. Like what the definition of an NPC is.
By your logic, players and DMs would never be able to play the game, because they wouldn't know what to do when they saw a creature listed as "casting a fireball at 20th level" and no other rules were immediately following. I mean, if they aren't using PC rules, then how would anyone know how to cast a fireball at 20th level and what it did? I think most of us can agree that's a pretty silly position to take.
5e defines NPC's as ANYTHING that's not a PC. The notion of a third type - Monster - doesn't exist in 5e and hasn't existed since 3e at the least.
Once again, this is demonstratably false. 5e defines NPCs as:
A nonplayer character is any character controlled by the Dungeon Master. NPCs can be enemies or allies, regular folk or named monsters.
It's not anything that's not a PC. Monsters do exist. Only named ones are considered NPCs.