It would be an interesting experiment, but where would you stop? So, once they sent all the white people back to Europe, all the black people back to Africa, and then all of the non-Aztec, Mayan, and Incan hispanics back to Spain, and all of the Asians back to Asia, what then? Would then we split those countries up into groups based around the first people to settle in that location? How could you even do that with all of the intermixing of ethnicities, tribes, races, etc.?
I mean, the Native Americans came from somewhere else too, and in more than one migration. How do we sort them out? Do they have to go back to Siberia and the Pacific Islands?
https://time.com/3964634/native-american-origin-theory/