1) I do think that non-humans have the ability to use language. Being that non-humans don't have the ability to speak words themselves or comprehend the full complexity of the human language, I could see why people would be quick to assume that non-humans can't use language. However, our human language is not the only form of language communication there is. Apart from the language we use to speak, there is body language. Humans use body language or facial expressions to communicate in many ways. In that same way, non-humans (such as animals) use their own form of language for communication. For example, if a dog walks up to another dog that is growling or presents a defensive stance, the other dog knows it is not welcome and should not get any closer. Also, two birds in a tree will use different chirps or whistles to communicate with one another. Those instinctual practices are those species' own methods of communication using their own form of language. Just because their language is different from our own or we don't understand what they know to be language, doesn't mean that they aren't capable of using those ways to communicate. The article Human and Non-Human Communication helps to illustrate more ways in which different kinds of animals use their own language to communicate. The conclusion of that article says, "human facial expression, (aspects of) human "body language", and (aspects of) human voice modulation in speaking, seem quite similar in kind to animal displays, and indeed similar in detail in many cases to the expressions and gestures of other primates."
Works Cited

Liberman, M. (n.d.). Human and Non-Human Communication.

2) Intelligence is "personal attributes that center around skill at information processing, problem solving, and adapting to new or changing environments." A person with intelligence is able to take in new information and concepts, form some level of understanding of that information, find logical and plausible solutions to the problems they are presented with, and can thrive in any environment they may find themselves in. In my opinion, there are different kinds of intelligence as well as multiple defining factors. There are people who are capable of solving any kind of scholastic problem; then, there are people who are capable of solving any kind of everyday problem. In other words, there are people who are street wise and people who are book wise. Every person posses either one, both, or neither of these forms of intelligence. With that being said, measuring intelligence is not as black and white as it may seem. Intelligence can be a very subjective characteristic. For example, a person who knows very little among people who know nothing would be considered intelligent. In the same way, a person who knows little among people who know a lot would be considered an unintelligent person.