The genocidal stories in the Old Testament are very troubling to those who bother to think about them at all. Accounts of the Hebrews wiping out entire cities are a bit too reminiscent of atrocities, like the Holocaust. The idea that such practices could be God sanctioned should and does raise many questions.
I consider these stories as metaphorical, with a very powerful real world lesson. If the solution to human misbehavior, sinfulness if you prefer, involves eliminating sinners, then that elimination must be complete and absolute. Sinners and potential sinners alike must be destroyed together.
The story of the Noahic Flood is a perfect example. God is said to embark on an effort to eradicate sin from the earth, He takes a rather ruthless approach in destroying all but eight human beings. That seems drastic enough but just note the result. It is total failure. Before the earth can dry out, Noah is already involved in sin. Clearly if human destruction is the proper response to sinfulness, then that destruction has to include everyone. God must start over with robots, not free moral agents.
So, if we choose to see the biblical genocides as lessons in sin management, we need to draw a different conclusion than what traditional Christianity has. The destruction of sinners as a remedy to sin is impossible, short of annihilating all humanity.
By extension we should recognize that the destruction of sinners could not be a part of Jesus either. What did not work before Christ, did not suddenly become the solution because of Jesus. If God's response to one sinner is his destruction, it has to be the same for every last one, no exceptions allowed. Sin management by destruction can only be merciless