but whenever we face a virus that contagious and deadly.
Exactly. It's not the first, won't be the last, nor is it "the big one". Nevertheless, it is contagious and deadly, hence the precautions.
Nobody likes lockdowns, however they'd dislike a Brazil situation even more.
The alternative would have been to let our health care systems collapse
This is also correct. It's not just the NHS or Polish medical system that would have collapsed though; a densely-populated and developed society involves a whole matrix of logistics, services, infrastructure that all depend/depends on the people who work in it/them to be actually well enough to turn up to work, get the food delivered to the shops, keep the shops open, get the kids taught, wipe the geriatrics' arses, keep prisoners, long-term psychiatric inpatients fed and watered, put out the fires, arrest the bad guys, get the trains, trams and buses driven, keep the power stations and gas pipes operated, the oil/gas rigs extracting, and keep the hospitals open.
Modern urban society has its vulnerabilities. Governments are aware of this, and the better organised ones have contingencies. Not contingencies to prevent things breaking down, but contingencies to prevent everything breaking down at the same time. The idea that most people are three meals away from rioting and violence is only a slight exaggeration.