That is a goal for humans. An animal doesn't care if it lives on Earth or Mars.
If animals do not care if they are alive on Earth or Mars, it suggests that human life is more valuable than animal life. Taking a stance on such a topic requires some attributes which animals lack compared to humans.
We take "life" as something inherently good and "death" as something inherently bad. Therefore we see value in the idea of spreading to other planets to survive longer. If we see dying and living both as part of a process, there is no saying if spreading to other planets is a good or a bad thing. The extinction of the human race might as well be part of a process that we are the only beings capable of feeling anxious about.