Most aliens will be stuck at their place of origin because they lack the intelligence to escape. I happen to think less intelligent life probably exists all over the place, and maybe even on moons in our own solar system.
That being said it's also extremely unlikely that we're the smartest creatures in the universe. There are probably life forms that make us look completely stupid by comparison. There's really no knowing how rare that kind of intelligence is though.
We may never find other creatures as smart as or smarter than us. Though it's also possible that what we would consider advanced intelligence isn't as rare as we think. We're only the smartest creatures on one planet. It's hard to know how that stacks up universally.
If you lined up all of the smartest creatures from a billion different planets where would we really fall on the hierarchy? Your guess is as good as mine.