Surely you must have some system for valuing certain forms of life over others, otherwise functioning is not really possible given the reality we find ourselves in. For example, pretty much anyone at some level values the lives of humans or more intelligent animals over the lives of, say, mosquitos, cockroaches, flies, etc, but those insects are animals too after all. (And while one certainly might put some value on some insects, I know if I find a ladybug inside I'm decently likely to try to take it outside without hurting it, I've never met anyone who would get as worked up about a dead bug as they would a dead cat, or put the same effort into saving a spider that they would into saving another person from a deadly situation. Clearly, the value of such animals is at some level held to be less.) Even further, it would be even more strange to value other living creatures as much as humans, like plants or bacteria (indeed, considering that one involuntarily kills countless bacteria just by existing and must consume plants to live, a hypothetical person who cared just as much about them as people would either have absolutely no regard for the lives of others, or would be consumed by constant guilt to the point of probably being unable to survive in the long run). Clearly then, just about everyone has some sort of hierarchy of what animals are more valuable than others, whether one consciously believes it or not. If intelligence is the metric that one uses to decide this, then one must value humans more than any known animal, because while some are smart, no animal is quite as smart as humans are. If intelligence is not the metric you use, then what is?