Although sex is necessary for reproduction, it's not performed solely for reproduction by humans, so it's entirely reasonable for us to want to more cleanly separate the different functions. (Pleasure, bonding, procreation, etc..)

The entire idea of human life is anachronistic in the sense that you're using it--tissue culture cells are alive, but nobody cares about killing them, nor is it okay to kill a person as long as you retain some of them alive in culture.

What we value is something that we might term personhood: like many things, it is hard to define exactly, but it is what triggers our moral intuitions and is some sort of recognition of being the kind of conscious creature that we humans are. At fertilization, there is no personhood, and given that it seems inexorably dependent on brain structure (in that generally if someone is brain-dead even if we can keep their body alive, we're generally comfortable saying that "they" are dead--the person is gone) we awkwardly have to account for the likely reality that personhood develops gradually. Once someone has full personhood, though, whatever that means, we ascribe the full set of rights to them.

However, for much of development, there is clearly no "person", only the potential to be one, so aside from superstitions and/or overzealous moral intuitions prompted by the need to care for babies, there isn't any issue of the baby having rights before it is a person. So, consequently, early abortions do not involve conflicting rights in the way in which you describe: only the mother is a person and she has rights.

If you want pro-choice people to clarify their stances in cases where there are plausibly a conflict of rights, you need to set up a clear scenario: can you "abort" a just-born baby? What about a baby whose head has crowned but who hasn't been born yet? What about during labor? What about if your waters have broken but you haven't started labor (but could be induced)? And so on.

But you really should understand the biological process much, much better. If you don't understand what you're talking about, it's very hard to have an opinion worth considering.