People on earth are a mix of the original people born here and different extraterrestrial civilizations.
The original Cosmic Plan was to create human beings originated on earth with no external influences. Because earth is in a kind of cosmic highway, there were ETs that:
1) Crashed here without being able to go back to their planet.
2) Some where deported here.
3) There were some that came to earth because their planet was destroyed.
4) Some took Men's daughters as theirs and procreated hybrids which became the Atlantis civilization.
Since then, all people on earth have on their DNA, sources from all.
Blood type RH negative, scientists attribute it to extraterrestrial origins. Since our common ancestor with primates which have the same 99% of our DNA don't have it. 10% of world population has it, mostly concentrated in France and Spain.
Links:
Book of Enoch chapter 7. Angels taking wifes with daughters of men