I've thought about this and the different ways it might play out.
We might somehow discover another planet and visit it. Or maybe contact is made here on earth. The easy case is when the life we discover is intelligent, but not enough to create civilizations. We would still clearly be at the top.
But what if they are smarter than us? I mean, what would it really be like to have to acknowledge that we're inferior, no matter how hard we try? That even if they shared technology with us, we're still just humans and can never be as intelligent as them. I mean a clear, marked difference between, like between apes and humans. Only this time, we're the apes. That seems hard to accept -- That we can be smart enough to have so much knowledge and culture, and still be below some other species. How would we deal with that?
Now on the other hand, what if we discovered a civilization that was some place in the grey area between ourselves and apes? Smart enough to have some language and social structure that we can recognize, but still clearly below us. How would we deal with them? What would that be like?
And what if we weren't able to tell which species was more intelligent than the other? How about if we seemed extremely intelligent in some areas, like creating inventions and machines, and they were better at something else, in ways we can't even imagine? What then?