All civilizations fall. Follows a pattern. We are in process. Amazing how blind citizens for the most part are.
What is astonishing and different with the USA is the sheer speed of self-destruction. It took centuries for former empires (Roman, Byzantine) to destroy themselves. We are doing it in a few snort decades.
Because literacy was not widespread, the self-realization and awareness of the decline of previous empires was probably minimal. There were no printed books, no media. Lifespans were short, so living memory was short. People heard of the glory of the old days through legends and family lore. Few people were educated or went to school, so people didn’t have the knowledge to look to history for examples of previous empire decline.