Humans, like so many species, care about their young, most likely for survival of the species. Evolution is a process that seems to be attempting to allow the best to survive and flourish. But the best is subjective.
Our brains have allowed us to place unwarranted significance upon ourselves as a species. We think we are special, because we think we are special. The idea that we are special, comes solely from us, and thus has no meaning in nature or the evolution of life itself. We are here because we are here, and because we can use our own language to describe anything, in whatever way we choose, we make all of the rules. What would life be without a sentient species to even acknowledge it?
If evolution is what science believes it to be, then we are nothing more than one of the current branches of life, started billions of years in the past, and not since broken. Life since it's apparent beginning, is so far immortal, and we are only a tiny fraction of the whole. Yet we are the species able to self-procalim ourselves to be better, or smarter, or more deserving of a place in the chain. So we are in a sense, selfish, but still completely unworthy of natures recognition as anything more than plankton.
That we argue endlessly over "precious" life, and when it may or may not begin, is laughable from the perspective of nature. Nature appears not to give two shits whether we exist or not, judging by the far exceeding number of extinct species over those that have managed to survive. We are not special, we are just people. And life for us begins when we get pregnant. The egg and sperm are united, and if all goes well, we get a baby, usually by choice.
But we are also the same species that gets to decide when we do not want to have a baby. And that sometimes comes after a pregnancy occurs. thus, we have abortions to end the chance of having an actual baby. Many people can't stand the thought, while many others believe it is truly none of their business what another human decides to do. Life began billions of years ago, and today we have 7 billion humans inhabiting the earth. The decision to have a baby or end a pregnancy still belongs to individuals, thankfully.