Further low 10’s of millions of deaths on its own really doesn’t explain the 90% population drop across several hundred years here. Smallpox killed between 65% to 95% of Native American populations but it was far from alone. We’re talking devastating plague after plague for generations which canceled out the tendency for populations to rebound when competition is low. Something like 200+ million deaths on the conservative side over a few hundred years not just one or two devastating but short lived outbreaks.
I haven’t heard of this - do you have any material to recommend on the subject?
Disease we can't explain that spread a few decades after European ships full of plagues arrived.
I mean, yeah, sure.
The fact that Europe didn't have the same catastrophic population decline suggests that either that didn't happen (possible, but a stretch) or that Europeans already had immunity.
Which would only be true if there was some freak genetic immunity (also a stretch) or the disease was already in wide circulation (far more likely).