This is your assumption based on what you currently know.
Wait
what?
I mean, with all the atmosphere and the gravity well, and the pesky humans, and the potentially poisonous air and whatnot. Sol
does have an oort cloud...
I think you will be able to look up the statistics of how many Ecuadorians alone there are living in (especially) Spain and Italy, and other countries of Europe. Even those figures lie, as a good many more are there illegally. Then there's the rest of Latin America.
Yes, but aren't these people primarily descended from Europeans?
So, is that what could happen if we are invaded by aliens? We get back at them two to five centuries later?
Depends on the definition of "get back". Illegal humans? That's an amusing concept...
By the word "native" I am assuming that you are using it in its correct sense, as in "born" somewhere, and don't mean specifically Chief Sitting Bull or Tupac Yupanqui, yes?
Yes, native as in born somewhere. I'm native to South Africa, although many people would like to believe otherwise due to my heritage.
When I speak of "Native Americans" though, I'm talking about the people that came to America thousands of years ago via the bearing strait land bridge.
EDIT:
and often for bringing in the new ones as well.
Such as?
For any civilization likely to be able to get here, yes.
Or some who cannot?
Ok, so maybe mining NEOs and oort objects isn't the easiest task, but if you're
going to other star systems for resources, you should be able to do it.
Maybe there's a scenario where the people entering the solar system are not geared up for ISRU, or they're in a bad way. But that is hardly a reason to invade Earth and pillage our resources.