Most of the universe is void. Most of the rest is whatever dark matter is. What we consider to be the entirety of material reality is a fraction of a fraction, and out of that, as far as we can tell, Earth has the only life that exists. There's probably more life out there, but if there is, as the Fermi Paradox points out, they're awfully quiet.

I think it's fair to assume that life will have practically zero impact on the universe. Even if the universe was teeming with it, it would be of such little significance at scale that it might as well be a rounding error in reality.