That's not depressing. It gives us a moral imperative to transplant Earth-origin life onto every somewhat concentrated mass that we can reach.
Then we can wait a few billion years, and the universe will likely have generated a superior successor species which can then re-seed over everything we had previously tilled, and then some.
And they'll all be rubber-forehead aliens to one another, because they'll be billionth cousins, a few million times removed.
Think about it, in so many sci Fi, the aliens are pretty similar to us. Carbon based, have DNA, etc.
If we seeded the galaxy with our life then a billion years from now we might get a star wars type reality where many species coexist together all because we seeded every corner of the galaxy.
Then we will either be literally extinct or at least economically extinct--permanently unable to recover space-launch technology. Then Earth has to gin up another dominant species capable of reaching the stars with whatever time it may have remaining.
We already have the technology to reach outside the solar system. It launched in 1977.
We will have the capability to transplant microorganisms to extrasolar planets long before moving humans that may have 100kg or more to one. Which is good, because it may take a while for the algae to get established anyway. And if for some reason higher species never show up, that celestial object won't have to overcome the steep initial hurdle of abiogenesis.
Then we can wait a few billion years, and the universe will likely have generated a superior successor species which can then re-seed over everything we had previously tilled, and then some.
And they'll all be rubber-forehead aliens to one another, because they'll be billionth cousins, a few million times removed.