Lots have people have speculated about what will happen if alien settlers were to arrive in our solar system. Some people think they would be super-evolved, perhaps beings of pure energy, who would help us achieve some heretofore unattainable state of enlightenment. Others think they would see our wars, diseases, etc. and annihilate us out of a sense of moral outrage. And still others think we would find a way to work together and construct a mutually beneficial bi-species society.
Personally, I think any aliens advanced enough to make it here will be so far ahead of us that they will be to us as we are to an ant colony. Do we help ants attain higher states of consciousness? Of course not. They're just ants.
Likewise, we don't get outraged over their moral failings. Sure, they are ruled by a tyrannical queen. Their societies aren't free at all. So what? They're just ants.
We ignore ants until they bother us. Then we kick over their anthills, or saturate them with insecticide, or douse them with gasoline and set them on fire. When the ant genocide is complete, we forget about them and continue on with our lives as if nothing happened.
When aliens arrive, I expect them to treat us the same way. They'll ignore us. Until we annoy them, that is, in which case they'll simply eradicate us. Because to them, we're just ants.