American Exceptionalism is not an easy concept for some. It requires a real appreciation of nuance instead of mindlessly equating it with jingoism. The Left lacks the necessary intellectual acuity.
They purposely equate it with "we're best" instead of how it is meant - that our country was founded with the acknowledgment that our freedom and liberty is given to us by God.
Of course such an idea must be torn down in order for the Left to "give us" what they choose to give us (or take away from us).