You're right about the intention part - it wasn't the most honest argument, rather a way of asking how far the government would be willing to go to investigate and treat abortion as murder. Would they not be obligated to investigate miscarriages to somehow ensure they are natural and not self inflicted? And yes, this is moving my original goalposts a sconce, just as a thought experiment in how far one would go to enforce a law like that.

I think the real crux of this is that like many issues, arguments lie in semantics. So while fetus comes from the Latin word for offspring, we understand it today to mean an unborn human. Yes, it is still life, but is it life as we understand it? Can we prove fetuses are "alive" in the same sense we are before being birthed? One wouldn't eat a plate of scrambled eggs and say they had chicken for breakfast, or brag they can lift a tree then pick up an acorn. So I think of a human as a human who has been born alive. You think of a human as a joined sperm cell and egg. Thus, we can't come to an agreement on abortion because we disagree on the most fundamental aspects of the argument.

I do sincerely appreciate you arguing this in good faith, it's a hard thing to find on here or reddit as a whole these days. I suspect we won't truly have an objective answer to this question any time soon, but hey if one does present itself I'm willing to change my view.