There is a meme in our culture, which equates the "natural selection" part of the equation with "survival of the fittest". But this misses the whole picture. Survival of the fittest is a survival strategy employed mainly by predators. Much of the rest of nature employs the "survival of the most useful" strategy with a great degree of success. In fact, the more evolved and complex a biosphere is, the more of this second type of strategy you can find in there.
You overlook a simple logical inference here. If some living creature is not a predator then it is preyed upon, i.e. the rest of nature is prey to your predators (by definition), so it inevitably falls victim for the second time, now to that survival of the fittest strategy...
