He is only a part of nature. How I view myself. My value is not any greater than other things. All life is sacred. Hence killing an animal for food is murder.
Human value is arbitrary and subjective.
Since there is no objective or transcendent source of value, all value is assigned by my peers, based on certain criteria. Francis Crick has advocated that newborn babies not be declared legally alive until after two days when they have been certified as healthly by medical examiners. In other words, they must meet certain physical criteria. Hitler decided to get rid of useless eaters. Some say today abortion is better than welfare which strains our resources.