Human flourishing has been pretty much linked with allowing people to kill other people since, well, forever.
I've been listening to this thing lately called "Fall of Civilizations Podcast." It is very well researched, and the creator/presenter does a fantastic job of drawing you into the story of how many well known (and some lesser known) ancient civilizations - from the ones that sprang up in river valleys in the near east to the early Americas and China - arose, thrived, and ultimately collapsed.
Sumeria, Akkad, Babylon, Han China, Carthage, Easter Island, the Aztec and Inca empires, etc. etc. etc. One thing that stood out for me is how for most of the history of human "civilization," the lives of individuals have been astonishingly cheap. This narrative the "pro-life" crowd has been selling that "since the dawn of time, each life has been treated as a precious gift of god" is utter bullshit.
I mean, if you were a king in Medieval Europe, took a second cousin as a wife when she was 15, she pushed out 8 kids by the time she was 25, half of them survived (none of them sons) and then she died giving birth to the 9th girl, you'd just go out and marry another teenager so you could get a male "heir to the throne."
Good 'ole traditional Christian family values!
Since...oh...about 1973...this false narrative has been pushed that "every life, no matter how nascent, has always been sacred and must be protected at all costs" and it is a fiction.