Even though functionalism was not my assigned definition, I enjoyed listening and discussing the viewpoint of functionalists and whether or not this was a good theory of consciousness to believe in. I believe functionalism is a better alternative to behaviorism and the identity theory because it encompasses some aspects of both. Functionalists believe that purely the functional roles control the different mental states. This includes the behavioral side of mental states as well as the physical side, such as neural activity and physiological sensations. Some may be able to criticize that the nature of consciousness is not functional even though it may have functional characteristics. This includes the idea that people exist in the world without a conscious, even though this is a controversial idea. I think consciousness is mainly what makes a living, breathing, functioning human being a person. I do not think that there are humans that exist without a consciousness, and even if these such humans did exist, I do not think they would be considered “people”. They may act and behave the way we do, but that missing piece of human consciousness would keep them from understanding what ‘normal’ people (conscious people) feel and believe.
I agree with you that humans perhaps lose some of their “human” qualities if they are not a conscious being. If functionalism is how you explain consciousness, though, then you would have to say that some machines, like computers, are conscious. I think a functionalist needs to look for another quality than consciousness to describe non-humans, given that a functionalist could say that many non-human things are conscious.