Last time I checked China had much lower immigration numbers than the US.
Immigration is not just about importing people. It's about importing a culture that is better suited for the demands of your society's ambitions. On the surface it's about bringing in people but really it's about bringing in a people.
Nope, America largely exterminated its native cultures hundreds of years ago. The culture that exists today is the immigrant culture of nation founded on ideas (freedom, slavery, capitalism, democracy) not bloodlines. America can be for anyone who wants to be part of that story.