Our world has a real love hate relationship with our fellow animals. We love our dogs and cats, but we raise cows, chickens, pigs and other animals by the millions, just to eat them.
I love eggs, but I don't eat chicken. Somewhere along the way I abhorred the commercialization, but still eat beef, pork and fish, and sometimes feel guilty doing so.
What if someday we were invaded by an alien force that crushed our militaries, then rounded up all the humans and put us in cages for breeding and consumption. Tear down all of our cities and build their own structures.
The animals that we eat would be set free or used as pets, and ground human would become one of their culinary staples. Leg of human would be a delicacy, female breasts would be used for sandwiches, genitalia as appetizers. Our skin would me made into clothing.
Hey, we have a great planet, with billions of people. A roaming band of aliens would find this place a perfect spot to set up camp.