Humans are unique in their ability to assign abstract values to inherently non-functional and otherwise useless objects. A diamond ring, a thousand dollar bill, or a gold bar has no more value to an animal than a smooth pebble, shiny rock, or fuzzy leaf. Animals cannot even assign value to their own lives. Apart from survival instincts and some mutually beneficial biological relationships, animals either ignore or eat one another. Tears are never shed as one group of animals seek to destroy another in their own quest for survival.
Animals make no judgments concerning the value of biological life.
Only man is capable of recognizing the value of animal life and seeking to protect it. If human value is set by the mutual consent of other humans, it is subject to change at any time. This has happened countless times throughout history. Many ancient cultures sacrificed live children in order to pacify the gods. Not all that long ago the U.S. Supreme Court declared slavery legal, effectively removing human status from Negroes.