The "Golden Era" of sci-fi in the 30s - a delay from the roaring 20s perhaps? - has a lot of stuff along the general lines of "Englishman (never Englishwoman mind you), often from some minor noble heritage, through mysterious means unknown ends up in an area of savages, but through the power of their greater Intelligence, becomes stronger, faster, and outer-smartier than all of those that they outsmart b/c they are smart I tell you, so smart!"

Idiocracy - and Marching Morons I see, and Time Machine as well from 1895 - is thus very much in line with the norm, with the twist that the savage lands are the future from now; the implication being that humanity has not only "reached its peak over all those that came before", but also "peaked, then declined, so that we - here, now - are the pinnacle of all civilization that ever was or ever will be".:-P Which there is a large degree of truth to that - e.g. antibiotic resistance and the enshittification of the internet and the state of ThE eCoNoMy ThO all reveal that we now have less than we ourselves did 10-20 years ago, even if for some that refers more to potential than actual.