I clarify:
Let’s say scientists can’t come up with solutions to global problems, AI gets out of control and turns almost everyone into paperclips during wars, and in the 2040s or 2050s, the surviving people (about a few tens of millions around the world or even less) gradually return to the level of intelligence of their distant ancestors?
A fun example of that, there’s been time and again where prototypes of things we now think of as modern were made about 2000 years before. But they didn’t have the prerequisite tools and information to make it anything more than that.
Like “Hero’s Engine”, a thousand of years old toy that’s a fully working Steam Engine. But cause they weren’t good enough at metallurgy yet, they knew it could work bigger but didn’t have any methods to make it bigger