The country was founded by people in quest of freedom - particularly economic & religious freedom. True, there were many backgrounds, but the motto e pluribus unum (out of many, one), unites us. Not "united in government", united in a freedom/liberty mindset. Our sovereignty resides in the hands of the people.
But things change along the way. It's like the guy who boasts having an "original" Abe Lincoln axe in his garage. But over the years, wear & tear have necessitated that the handle be changed twice & the axe head 3 times.