Value Of Life For Humans Compared To Other Animals?

Why should a human's life be valued more compared to other animals? Considering there do exist some biologically immortal animals, should their lives be valued more than a human's relatively smaller lifespan? Shouldn't an immortal's life be valued much more than a mortal's life that is fated to die and stay dead for a long time anyways? And even for non-biologically immortal beings that live longer lifespans, like turtles, shouldn't their lives matter more than humans? Furthermore, when is it moral to kill a human to save an animal. Considering eating meat leads to animal death, is it moral to kill a human to save an animal life? 

Also, should making humans immortal be a fundamental goal for humanity? What is the value and meaning of life if we all are just going to stay dead in the long-term? At the end of the day, life is just short-term and not something long-term.