Humans can be classified in the clade of mammals (mammary glands are a sign of a mammal). Also alot of people talk about individuality, the soul and individual needs.
If humans have souls then animals also have souls. And so if humans have individuality and individual needs, so do animals. When humans kill other animals they are killing mammals. Also to kill another soul is weird. What about the individual being killed, do they not have a right to life as much as the killer?
Even if you do not believe in souls, the actual act of killing other innocent animals by humans is weird.
Especially when there is no need to, it is based on greed and illogical selfish ideas!