I am 86 and from my time in a parochial grade school as a son of immigrants I remember being told that the USA was an exceptional government created by the Founders. My brother who was killed on Okinawa and myself who also served overseas in WWII went into service believing such. Perhaps one can take issue with the specific word expression ‘exceptionalism’ but I will argue the meaning of being exceptional is valid. That is at least until a bunch of immigrants and non caring citizens started being/thinking otherwise.
As a kid in school, I just thought american was america and a great place to live in....But with a catholic education, you were taught better than us public school kids...my husband went to St Thomas until the 10 grade and the nun’s asked him to leave, then he went to Aero-mechanics for 1 year and they asked him to leave. His senior year at Pershing High school was went I met him....he said the stuff they were teaching seniors he got in the 10th grade at St Thomas before he and 3 of his friends were asked nicely to leave....those nuns knew how to teach....
All nations have their founding myths that may sound ridiculous, tiresome or offensive to outsiders, and are intended for domestic consumption. Such is the concept of ‘American exceptionalism’. It does refer, as stated above, among other things to our constitution, which was exceptional in the 18th century, but is no longer exceptional as others have developed their own based on ours or not, improved or not, so that ours can be said to be archaic in parts (certainly not those parts that Marxist Obama disdains and wants to improve but in the meantime ignores.)