Mexicans are NOT all that good at fighting wars, IIRC about 50 conquistadors showed up on horseback at what would later be called Mexico City, and Montezuma and the Aztecs surrendered almost immediately! ;)
Actually, while the Spanish were hardy and fierce, they won because they had 200,000 Tlaxcalan Indian allies who were tired of being sacrificed, having their hearts torn out, and then being eaten by the Aztecs. This cannibalism was a significant source of protein for the Aztecs who had no cows, horses, sheep, or goats for protein. They ate ducks, fish, and turkeys, corn, squash, other vegetables, probably a few fruits, and chocolate for the rich. The Spaniards subsequently rewarded the Tlaxcalan by cheating them out of their land as much as possible.
If you really care, read Cortez’s 5 Letters to King Carlos of Spain and Bernal Diaz’s story of the conquest written from a lieutenant’s viewpoint. The fighting was brutal and vicious on both sides. If I remember correctly, oh heck, I’ll go find a link. OK, here is a link, and it includes clickable sources of early and original information.
https://en.wikipedia.org/wiki/Spanish_conquest_of_the_Aztec_Empire
There were 300+ conquistadors plus allies who hated the Aztecs. The latter were not trying to kill their enemies. They wanted to capture them alive for sacrifice to their gods. The Spanish killed them at will.