I'm struggling to be as clear as can be here. Is a person who rapes and murders children evil? Is raping and murdering children evil? Yes or no. Anybody.
First, there's no raping mentioned in the Bible to be legal. As a war practice adapted by all Canaanites that the winner will take everything. For the Jews own survival, God allows them to adapt an eye for eye and tooth for tooth policy. They thus take whatever from their Canaanite enemies. As a war practice woman are taken as a human resources to give birth to labors and warriors. The Jews took only the virgins for the reason that virgins will adapt their husbands' religion, while non-virgins already adapted the religions of the Canaanites.
God has a reason to command the Jews to eradicate the Canaanites as God's priority here on earth is to save souls. We humans count lives as a physical death. However to God every human will have to die once in one way or another. God counts lives as whether the souls are savable. So the Canaanites whose souls are not savable, God will have to remove them as a whole for the Jews to survive the history to bring forward His salvation to save more human souls. If the Canaanites are allowed to live, while the Jews were outnumbered, then the Jews would have been the first to be wiped out completely.
As for children when they grow up they will kill the Jews and thus will wind up in hell. Is that what you want? If no then accept God's way of allowing them to die as children such that the judgment of Law won't apply to them.
It is after the Jews successfully settled in Canaan that God strictly ask them not to kill as one of the 10 commandments.
