TL;DR - native alliances were important, but Spanish armor made them nearly invincible against native weapons, their military tactics were superior, and cavalry were extremely overpowered against armies made up only of footsoldiers. Weaponry and tech were certainly not irrelevant.
TL;DR - native alliances were important, but Spanish armor made them nearly invincible against native weapons, their military tactics were superior, and cavalry were extremely overpowered against armies made up only of footsoldiers. Weaponry and tech were certainly not irrelevant.