> one clearly dominates
Even if we agreed that life begins at conception, it's not at all clear to me that the bodily autonomy and privacy issues would go away.
> it would be better if the states wrote legislation that clearly defines human life
Except there's no objective answer in reality, because "human life" is a fuzzy made-up concept. I doubt some arbitrary legislation would settle things down. People would still disagree just as vehemently.