None of this had to happen. We could have had a real quarantine, just a month or two back in 2019, but that would require making slightly less money for a brief period of time, so instead we get to live in eternal plague world. The hobbling of any effective covid response by our ruling class in favor of more lucrative half-measures and non-measures is beyond a humanitarian disaster, it's a crime of unprecedented scale.

Yes it did. If all countries did this around the world many people would have starved to death. It's simply not ethical. Without eliminating it everywhere it would spread eventually - just look at Australia.

You can't even enforce a total lockdown in western countries without excluding "key workers" that would allow the virus to spread anyway.

Nothing you have suggested would work in the real world. The only solution to prevent this is new medicines and prophylactics. We have developed some of these in the form of antivirals but they are not used enough to stop the spread.

We already enjoy a level of health unknown to people 100 years ago even with COVID-19. There will always be new diseases and this is the nature of evolution unfortunately. Previous generations had to accept this, now we have to as well. I hate to say it but probably our current level of health and healthcare isn't sustainable without further advances thanks to antibiotic and antiviral resistance. We will need to change our approach going forward using things like bacteriophages, increased sanitation, healthier life styles, less cattle antibiotics, and new treatments to keep up.