I'm not sure there's a better term than "Barbarian." I think "Ravager" is worse, given the root of that word. "Berzerker" is alright, but it evokes a Norse heritage and the whole point of discarding "Barbarian" is getting rid of the cultural baggage. "Rager" is... too on the nose.
You could go with something generic like "Brawler" or "Roughneck," but those kind of terms have historically been applied to Rogue archetypes. "Warrior" is the best overall term, IMO, but that kind of prompts the question of the difference between warriors and fighters. "Warrior" is too generic and lacks the Barbarian class's nature and tribal flavor. You don't want to go with "Tribal Warrior" or "Wild Warrior" or "Wildsperson" because that still feels a little culturally condescending, and it may not describe every member of the class. "Wilderness Warrior" is okay... but that kind of steps on Ranger. Although getting stepped on really does feel like the Ranger's lot in life, stuck in the middle between the more well-defined classes of Fighter, Barbarian, Druid, Rogue, and Bard. "Rage Warrior"? Ugh, no.
How do you differentiate Fighter, Ranger and Barbarian without any cultural inclinations?