You're wrong when you say that animals can't communicate, and more so that they can't communicate with us. Because they can. And to a big extent, we can understand them.
The jobs of behaviorists is solely understanding behavior, specifically nonhuman animal behavior. I'll use the dog as an example, since it is a common element in society we interact with.
A dog can tell his owner exactly how he's feeling through body language...it's left to the owner to understand (which he can easily do through a quick google search). Wagging tail and perked up ears? He's happy. Butt in the air with attentive eyes and excited posture? He wants to play. Tail between legs, ears drooped down, and body shrunk in? He's scared. For a more advanced example, my dog will let me know he's hungry by circling around his bowl or actually bringing the bowl to me. Sometimes, if I'm upstairs he'll clank his nails on the bowl to catch me attention. I, as a human with superior self-awareness and general cognition (aka common sense), can interpret that my dog needs food in his bowl. Considering he has a food bowl and two water bowls and always brings me the food one, I'd say he understands patterns quite well.
But maybe you're not talking about domesticated animals. Well, it pretty much applies to the wild ones as well. Chimpanzees use hand gestures, facial expressions, and vocal sounds to get their messages across. They also live in a hierarchical society in which alphas run things. Failure to stay in line results in punishment, which is a form of communication and creates a stable pattern (ie. "Do this and something you don't like will happen). So I'd say that animals do have a sense of communication and patterns. Sure, it's not as advanced so the chimp in North America can get his point across to the chimp in Asia, but it does the job for immediate survival.
In conclusion, the communication and patterns of animals may not be as advanced as humans, but it certainly isn't the things that separates humans from nonhuman animals.