USA is people initially coming over to be independent from their home countries and from each other (not to form a nation), and then slowly merging (with some dragged-along without their will, like African-American slaves, and others coming from outside like post-US formation asian, european, etc immigrants) under the flag of freedom, opportunity, etc., in a period where a rising US global role tide lifted all domestic boats.

In the meantime a common US culture has formed too, but not one with any deep historical roots, and also one where many parts don't feel that close to now that the good times are not exactly continuing...