Don’t assume you know what I think it means.
It does mean there are certain things in war you should not do. And Biblical examples are not always about what you should do - only the nature of human beings and historical stories.
There’s no Christian justification for outright genocide. Thou shalt not murder. That does not mean to not defend yourself and not to win wars perpetuated upon you, but it doesn’t mean anything goes.
Numbers 31:1-18.
Your logic is flawed my FRiend. Very flawed in fact
The very one who SPOKE creation into existence is the very one has declared Himself to be the final judge in all matters of time, space and matter.
The same God holds the deed to the entire universe that we exist in has CHOSEN to reveal HIMSELF not only through creation but also through HIS only begotten SON - BORN physically into this world through a virgin named Mary - was crucified - died - buried and on the 3rd day rose again by HIS own power and authority will one day —. Soon return a 2nd time not as a baby but as conqueror and KING —. I digress.