While the US is pretty old as a state, most societies have a direct continuation from one state to the next. It’s not like when France overthrew its monarchy they stopped being France or seeing themselves as French. So they may see their continuous history as much older than the current state, with the Kingdom of France going back to 987.
The US doesn’t have a continuous history prior to 1776 because they mostly come from Britain but they denounce their British heritage and they settled in NA but also denounce the heritage of the local peoples there. So the average American sees their entire history as starting at 1776, maybe a little bit further back to include the initial colonies and that’s about it.
https://www.youtube.com/watch?v=mJDWPLlI5I4