This article does not mention the main cause of the conquest of the Aztec Empire—smallpox!!!!
https://www.pastmedicalhistory.co.uk/smallpox-and-the-conquest-of-mexico/
The main reason wasn’t even smallpox. It was a woman named Malinche who was multilingual who facilitated communication between Cortez and neighboring ally tribes AND the Aztecs. He could not have formed the alliances he needed to defeat them.
The thing about smallpox and other diseases is no one knew what caused it. It was believed “Bad Air”, a ‘witches hex’ or the ‘evil eye’ were the cause of it.