We have more knowledge accessible to us than ever before. If there was some kind of collapse, the first thing intelligent people would do is try to re-establish communication with others.

And we have some knowledge and habits that literally weren't available to anyone in the past, like knowing to keep our living areas clean and free of pests like rodents. To keep trash and human feces far away from where we live to avoid contamination.

We know the importance of water purification in a way that past civilizations did not understand. So we automatically avoid the diseases and ailments that 99% of humans in history weren't able to avoid. We know about scurvy and how easy it is to prevent, as another example.

So while it would be a huge shock and challenge for people, and I'm sure many would die, we would still be better able to handle survival than anyone that came before.