Everything in the visible Universe would cease to mean anything instantly because we're the only known form of matter capable of creating meaning.
What use is a beautiful planet if the Universe is bereft of species that can find planets beautiful?
That we know of. "Meaning" is subjective. If it were possible to communicate with worker bees, they would tell you that their life has meaning, that they have a purpose...we are the only ones who have created OUR sense of meaning, but if you watch an animal protect their young or a bird feeding their young, they too have meaning in their actions....
I've long said that humans are the "cancer" of the earth. However the hell we've gotten here we multiply at an enormous rate, kill the infrastructure, destroy the natural environment and will be the eventual death of the planet.