not against immigration
also my ancestors were here before any other europeans
Yes, but when they got here they drank 100 gallons of mead in celebration, some guy named Leif insulted some other guy named Bjorn, something to do with who had the most arm rings, and then they slaughtered each other. Doesn't count.
On a more serious note: I think these historical wrongs should be righted. And since it seems fair to redress them in the order they occurred, we can proceed from west to east. First, all the Asians and Hispanics leave the U.S. and go back to their respective countries. Hispanics, don't unpack, though. We'll be back to you shortly. Now the Africans must go back to Africa. That done the northern and central Europeans will all pack up and go back to their respective countries. Lastly the Spanish and Portugese must clear out of the southwestern U.S., Mexico, central and south America. And finally we have undone European immigration. The displaced native Americans may spread back out across the U.S. It's yours, but of course, you all displaced each other over and over for a thousand years, so you'll have to work out among yourselves who gets the best spots.
Ok, England is going to be a mess. I'm almost tempted to leave these wrongs unrighted. Only reasonable way to do it is draw some lines. All of you in the northwest of the country go to Ireland. Don't unpack, etc., etc. All of you in the south with dark skin, go to Spain. It goes without saying that most of you should also not unpack, and may want to purchase sunscreen. The folks on the east coast: if you're in the northeast go to Denmark. If you're in the southeast go to Germany. The people in Ireland with fair hair should now also go to Denmark, Finland, and Sweden. Those of you who are left are Celts. You can have both islands. As far as we know you didn't displace anyone.
Europe... damn. Ok, we have to take this in order. If you're northern European, and _do not_ have red hair or many freckles, you're going further north. If you are living in central Europe and have swarthy features, you get to draw lots: half of you go to Turkey and points south and east; the other half get to be Mongols and Huns, you go east. Now this will sound strange, but if you live in northern Spain, southern France, Switzerland, northern Italy, good chance you're Goths. Go east until you get to the Black Sea, then tramp north to Sweden. Italy... everyone south of Rome draw lots: half to northern Africa, half to Greece and the Adriatic and Aegean nations. Lastly, southern Spain, Portugal, Sicily, Sardinia, Crete, etc., put on that sunscreen and go across the med to northern Africa.
Now, despite there obviously being grave moral issues that remain unaddressed, I'm not sure how much further we can go with any confidence. I'm not touching the rest of Africa with a ten-foot pole, and good luck sorting out the migratory effects of the empires of the Egyptians, Babylonians, Assyrians, Minoans, Myceneans, Mesopotamians, etc. Eventually everyone has to end up back in south central Africa, or there will still be evil in our past.