How do I “acknowledge the other person’s humanity” when this person acts more like an animal than a person. Sorry for such a negative statement, but this is how this person behaves.
Please keep in mind the distinction between what Aristotle described as each person’s “potentiality” compared with the person’s “actuality” in behaving in accord with the moral virtues. The one you described as acting “like an animal” is not actualizing the potential for high level human behavior. Yet, this person still has the “potentiality” to achieve this, with proper virtues education and encouragement by wise people. As you see this potential, you are acknowledging the humanity in the other person.