Consider this... Even a dog can have a motivation. My half husky 1/4 chow 1/4 German Shepard has a motivation. Escape and procreate. I always know when the female across the street goes into heat. He somehow gets our chocolate lab/rott mix to push the dog house where its in the perfect position for Bear to climb on top of it, Jump onto the small makeshift roof my husband built to cover half the cage so they could get out of the rain, then use the tree beside the cage to climb down. Yes, I have a tree descending dog. He doesn't quite rise to the occasion of tree climber but he will try if he gets loose while the chickens are out and about eating bugs. One goes up the tree and Bear tries to go up after it....hence why they are in the cage.

If bear escapes by climbing instead of finding a weak point to chew through, and Wolf is stuck in the cage, Bear will head not for the chickens but for the female across the street. We really should have named them Pinky and the Brain.

But notice what they go after... Food, or at least something resembling food and procreation. Even single cell organisms want to survive and procreate. It is the one thing all living creatures have in common. Plants procreate just in different ways than we do. The praying mantis eats her mate, thank god we humans didn't evolve to do that.

My point is, they would have to be intelligent to find their way to us. The only way they wouldn't be is if we found our way to them. As far as motivations for coming here or anywhere other than their home planet... Food and Procreation... As to communication... Do you know how many of my neighbors can speak more than one language? No, me neither but I am willing to bet the retired Astrophysicist up the hill can speak several. Communication issues can be overcome with enough motivation.