You ask very good questions. Here's my two cents, maybe only two farthings.
It seems to me that from a world-historical perspective, we might be returning to normal rather than entering a NEW heinous phase. Ever since people began living bunched together in cities, they've experienced generational waves of infectious diseases. (The Great Plague of 1347-1352 was just the first and most severe of many recurrences, and in between times there were periodic waves of small pox et alia.)
We didn't grow up experiencing that because of the technological innovations of vaccines and antibiotics, but now there are so many humans, so interconnected, and so disrupting nature's reservoirs of disease that we'll probable see more waves of disease.
I don't despair, though. Our tools are much better than our ancestors had 700 years ago, from gene sequencing to communicating about disease, to the ability to mass-produce hand soap and face masks. Maybe this will produce lasting cultural changes that will help us resist diseases. Personally, I wouldn't mind moving to bowing rather than shaking hands and wearing a mask when I have a cold -- both very normal in a number of East Asian cultures.