We can all learn something from that. Knowing that we will all die, we should not focus on that. We should accept death as inevitable, and focus on living, here and now.
Knowing inevitably all life on Earth as we know has a beginning and an end, we should all learn to appreciate the fleeting moments we do have here with ourselves, with others, and with nature.
Perhaps the carefree, beautiful summer grasses we enjoy in our own backyards were once the location and the result of past battles for freedom or independence.
We may want to spend more time with those we love and realize what is truly important in this life while we are here. That is the part that is not pessimistic or optimistic. It just is, and knowing the impermanence of everything should help us learn to cherish every moment we have with everything. This is the beauty of truth.
We may not be able to change the inherent nature of life and behaviours, but we can lean to understand it, appreciate it, and see the beauty in everyday life.