I think that you hit the nail on the head. [this in reference to a specific bolded text] Using Barbarians for every culture that isn't "civilised" in a way easily recognizable from a Western POV is just silly. The Apache, so far as I know, never had berserkers of any kind. The Mongols didn't do drugs and work themselves into a frenzy. The various people of the Iroquois Federation didn't run mouth frothing into battle without care for self or tactics or sanity.
Instead, those are Fighters, Rogues, Rangers, Paladins, with different gear sets than their European counterparts.