In some of Asimov's work humanity had forgotten how certain key technologies worked but they were automated and kept working and sustaining civilisations for hundreds of years before collapsing. I think about that sometimes when I realise I forgot about a Kubernetes cluster that just kept running for a year or two.

Likewise in Warhammer 40K (which probably borrows a lot from its sci-fi predecessors), science and invention is pretty much dead and there's a religious sect that keeps technology and factories running. AI (Abominal Intelligence) is also outlawed, so instead they put the remains of human brains into machines if they need some autonomy / decision making.