Free will isn't a good thing...
Free will allows all of the problems I mentioned. Humanity doesn't deserve to have free will.
Catch them. Study them. Steal their technology. Find out where they came from. Plan invasion. Invade. Enslave. Colonize. Evolve into new species. War between Earth and Colony. One species is wiped out. Two species become one. One species becomes two. Then we go right back down to one a few millennia later.
Well if they came to our planet, their technology would be superior, and unless they don't have poseable thumbs I doubt they'd want to splice with us lol
Interstellar travel doesn't quite equate to automatically having military superiority. We would either kill them or drive them off in the attempt.
As we all know, NASA constantly beams up radio waves to outter space, hoping that one day they'll be received by some other civilization. But let's say we one day finally find out about some potential neighboors in outter space. What will we do?
That's possible, but I think odds are more likely that with superior technology comes superior military unless they're a harmonious race.
Really I think it would all come down to numbers. If they contacted us it would be a small reconnaissance and exploration force. Highly doubtful they would be able to beat the sheer number of bodies we would be able to hit them with.