People have been interested in civilization since the dawn of civilization, dude. Even when it collapses it regrows. We’re naturally social creatures and ideas don’t die. Even in times of decline people aspire to do better.

Medieval European peasants knew what Roman aqueducts were for. They knew that civilization had fallen, but they made a new one and eventually it regrew to the point of the previous Roman empire, and then beyond, through ups and downs, until now.

Not everyone remains interested the whole time, but it does carry forward.