Why live? What’s the meaning of life? What’s the purpose of life? I hope I don’t have to explain that people have been asking this question since we first were able to form words and start thinking. You’re going to get as many different opinions to answer this question as there are people to write a response. You could spend a lifetime studying philosophy and not find a definitive answer. And in the end you just have to decide for yourself which answer most speaks to you. Are you atheist, materialist, spiritual, philosophical? Take your pick.
Personally, I like Buddhist philosophy for these kinds of questions. And I suspect the Buddha would say that we are here because of craving for sense pleasures, craving for existence, and ignorance of our true nature and the true nature of reality. We live because we want to exist, we want to have experiences and feel the things that are available to us as living beings. Whether it’s food or sex or money or adventure or admiration or love we feel like getting the things we want will make us happy. The flip side of craving is aversion, where we feel like achieving separation from those things that are unpleasant will make us happy.
Volumes have been written about this and it’s impossible to summarize well in a single post. But if it speaks to you there’s a lot more to say about it.
“Now this, bhikkhus, is the noble truth of suffering: birth is suffering, aging is suffering, illness is suffering, death is suffering; union with what is displeasing is suffering; separation from what is pleasing is suffering; not to get what one wants is suffering; in brief, the five aggregates subject to clinging are suffering.”
He didn’t say anything specifically about the ethics of human reproduction. He taught that craving sense pleasures leads to suffering. The monks that followed him were celibate. But he knew few would follow that path. So he taught a simplified code of ethics for householders (don’t kill, don’t lie, etc.) and assumed that there would always be people who want to make more people. Rebirth was an important part of his doctrine. The volitional actions you perform in life create karma which then, after your death, produces another birth. Escaping the cycle of karma and rebirth by letting go of the concept of self, of the idea of me and mine, was the ultimate goal of his path. And it’s only possible to get there in a human body. So in that sense he was not an anti-natalist.