Which ones?

Certainly if 8,000[1] years ago a tribe walked across and settled, and then 7,000 years ago another group walked across and set up camp next to the descendants of that first tribe who had been there a thousand years, the second group were actually immigrants, right?

And how do we sort it out now, millennia after those various groups arrived, after all that DNA has been mixed together?

My point is just that it's silly to label any race or group "immigrant" or "native" based on what movements we guess from their skin color that their ancestors may have made millennia or centuries ago, or even what their parents did. Yes, I'm very in favor of birthright citizenship, even if people have "anchor babies" in bad faith the baby didn't have any say in it. And no one else of any color had any say in being born in America either.

[1] please substitute correct numbers -- they don't matter

What if they took the bus across?