So I think the real debate is over when it’s acceptable to kill a human at an early stage of development. That is fundamentally a moral compromise, in the same way that e.g. the law of self defense is a moral compromise. Nothing in science says a fetus has a “right to life” just as nothing in science says anyone has a “right to bodily autonomy.”
I think partisans and ideologues try to take this issue to extremes based on principle, but I think most people (especially mothers) have a mushy view. They know miscarriages happen naturally in the early weeks and so support some abortion right. They support exceptions for life of mother or fetal abnormalities even in later stages. But for they’ve also seen ultrasounds showing something that looks a lot like a baby at 15 weeks and aren’t ideological enough to think you should be able to kill that without a really good reason.
This is an interesting topic. The two questions I have, seem to be difficult for people to answer and have them be consistent in other areas of our law and culture.
1) What defines a human life from a logical perspective?
This one seems difficult. For example, you seem to think that if one cannot survive without medical treatment that they don't count as a life or are not worth protecting, yet this is inconsistent with our laws on things like duty of care to special needs individuals, children, or incapacitated people.
2) When is it acceptable to take, or not save, a life?
This is definitely and interesting topic.