Seiran about to be reunited with his waifu <3
Oh we getting something like the aztecs going extinct cause they got sick from spanish diseases.
I imagine it might be similar to how the natives of the Americas felt when ship after ship of Europeans started coming over.
A few corrections:
The Aztecs continued for a long time after Cortez, just without their religion. In fact, after the Spanish killed Moctezuma II, the very first thing the Aztec nobility did was sign up with the Spanish to go south and raid the Maya (or rather what was left of the Maya, their civilization having collapsed about 180 years before the Spanish arrived, and then having a second collapse again not too long before)
The Aztecs did such a good job at being warriors for the Spanish, Queen Isabella made Moctezuma's grandson a Spanish Duke as a reward, a peerage still held by his descendants.
https://en.wikipedia.org/wiki/Duke_of_Moctezuma_de_Tultengo
European diseases also had much less immediately devastating effect and more of an affect on birthrates. A century after the Spanish arrived, the population had only declined about 5%.
I am going to try to compress this very hard:
There are two types of smallpox, a "long" smallpox and a "short" one. The new world only got "long" small pox until the 1800s because anyone with "short" small pox would not have survived the trip over the atlantic until the invention of steam. Short small pox is the rather lethal strain.
Long smallpox, with care, has very high odds of survival, about the same as the flu - you will have the pox pustules and be extremely fatigued for about two weeks, and then the vast majority of people recover. The issue is "with care"; the problem is those two weeks and how virulent it is - that is, how fast it spreads and how likely it is you'll catch it. If everyone in a village catches long small pox at the same time, that means no one is there to care for anyone. No one is able to draw water or gather/cook food, and people die of hunger/thirst. There was no running water and EasyMac in the 1500s.
Spanish Flu in the 1910's was only about 5% lethality rate, but in areas heavily hit by the flu you saw populations decline by upto 20% - that delta is the number of people who died due daily life completely collapsing for two weeks.
So in remote Indian villages, were small pox spreads rapidly, everyone would get sick and due to the lack of stored food, people would might survive died instead. This had a knock over effect of the sick who could make it to the Spanish missions often survived because people were there to care for them until the symptoms passed. Thus more indians moved to the missions and well... they were worked like slaves and birthrates declined, so that by the 1700s the native population outside of Spanish cities and missions had collapsed drastically.
Another interesting note is that the Spanish court was aware of the decline of native population due to disease and mistreatment in the 1600s, and attempted everything they could think of to try to stop it and raise birthrates in New Spain.
This was because the native population was their workforce and without indians to work the plantations an mines, Spain's economy was suffering.
Anyway, tl;dr is that you have been lied to in school. European diseases did not cause a mass die-off, it caused a moderate reduction in birthrates that took centuries to reduce the native populations.
Cleanse the Xenos with the emperor's holy flame