[TX0098812]

Aren't coronaviruses pretty common...?

[Fomite]

Yes. They've also caused three major epidemics in the past two decades - there's no reason they shouldn't have emerged historically from time to time.

[Florin_Andrei]

So, a likely scenario is: a new virus appeared, it swept through the population, caused serious disease, a bunch of people died, the survivors had better resistance to it, it settled as a mostly innocuous thing (such as the common cold) or disappeared completely, and the next generations remembered it as "the plague of emperor Fancy Pants" or something.

[colechristensen]

Yes, people seem to miss this. There are several mild endemic coronavirus diseases in humans, usually called "common cold" along with many others.

[shoto_io]

Yes. But then again they didn’t start out as endemic virus but as a pandemic one. They probably wrecked a lot of havoc before becoming just a cold. Mayas and Aztecs can tell.