I disagree about the nephilim. They were gone after the flood. And the fallen angels were not allowed to materialize again. Tartarus comes to mind. 2 Pet 2:4 The Israelites just encountered unusually big people. Like today's NBA.
If Jah hadn't set those limits on the sinful angels then the line of Christ would have been under risk of being compromised like it had been pre-flood. That's my understanding of the flood anyway. It was an emergency purge system for the genetic bugfarkery that the fallen angels started. No way was God going to let that happen again.
Regarding the destruction of the women and children...in most cases the Isrealites didn't even do that and Jehovah didn't seem too insistent on it. He knew that it was to clear stumbling blocks from their way but if they felt they could live with them, so be it. Those children were probably sacrificed to Baal on a regular basis and sexually abused when they weren't. Death would have been a release for them. Horrible parents raising soon-to-be horrible adults. And the women? Well they were adults that decided to follow a life of extreme sin. It was on them.
In the end, Romans 9:15 "For he says to Moses, “I will have mercy on whom I have mercy, and I will have compassion on whom I have compassion.”"
There is nothing more merciful and compassionate than Jehovah resurrecting those women and children in a righteous new world. A world were they won't be abused and destroyed, both mentally and physically. Where they will fulfill their purpose and go on to be happy well adjusted people. Hopefully...