Yeah, the natives were aggressive alright, they were fighting each other long before the Europeans showed up.
Fighting over land and natural resources.
1200+ different tribes, some were allies, some hereditary enemies,
some were nomadic, others stayed in place, some were agrarians,
some were hunters, some were fishers,
they had no central government or unified nation,
half of them didn't even know the other half existed and vice versa.
Many tribes were brutal, they plundered, raped, tortured, killed and enslaved members of other tribes.
The Comanches were the worst, they were more vicious with captives of other tribes
than they were with captive whites. Skinned them alive, cut open the bellies of pregnant women, fed the babies to their dogs, stuff like that. Yeah, those natives, man, they were peace lovin folks fer shur.