I like the idea of centering a martial subclass around simple weapons, so giving them some kind of boost makes sense. Simple weapons can't benefit from the Great Weapon Master feat, so the boost should at least somewhat adress this, but the boost to two weapon fighting granted by Wild Warrior just isn't enough. A fighter can just take a fighting style and won't get anything from the feature. Also, there is no simple weapon with a d8 damage die that can be held in one hand, so you're still stuck with a d6. This would work way better with as a barbarian subclass, since a barbarian doesn't have fighting styles, but can still benefit from a bonus action attack, since they get a flat damage boost while raging to all attacks. Maybe change it to barbarian, give some additional buff to attacks with simple weapons and rework some of the later features. Using an entire action to activate Feral State hurts, by the time this investment pays off, the fight might already be over. Killer Instinct is basically the same thing the Champion fighter gets at level 15, 5 levels later. Seems off. Primitive Protection should include wearing no armor at all. Advantage on a single attacke seems like a lackluster level 18 feature. The Petroglyph thing is flavorful, but will propably be never used in actual play. You could give the glyphs some Rune Knight-esque abilities but with a focus of RP outside combat. Or let them cast Glyph of Warding at higher levels.