The idea of American exceptionalism is easily defended.
America is the only country or empire in recorded history to have the entire world at its feet (Summer 1945) and not take whatever it wanted. Not only did it not take whatever it wanted, it loaned money to the vanquished to rebuild. Of course that was self-serving (we needed a decent world economy), but it was also world-serving.
America even gave away Eastern Europe (freed of Nazism) to the Soviets (Communist dictatorship).
If episodes in history are going to be compared, they need to be compared to the wonderful paradises that the Commies wish we would become.
One thing you left out. Unlike the Mongols, Aztecs, Native Americans, Turks, Zulu and other African tribes, when the United States of America had the entire world at its feet in late 1945 in addition to the world’s ONLY Atomic bombs, under American policy THE KILLING STOPPED.
When “others” were victorious, they got down to the real killing.
That’s one thing exceptional about the United States.