As usual, the elephant in the room goes unremarked: the Old Testament (specifically the parts under discussion here) is not factual history but propaganda. Evolution may be harsh and amoral, but it really happened; we are the result of hundreds of millions of years of tooth-and-claw survival. But rather than deify evolution and worship its values, we have the option—some would say the only right option on meeting a god—of killing it and taking its powers for our own use.
The Old Testament God has no such excuse. The stories of genocides were almost certainly not told because they actually happened, but rather because the compilers of the OT regarded these genocidal commands as being consistent with the kind of god that they wanted; they embraced the idea of slaughter rather than rejecting it. (Archaeology gives us a history of the Levant which is completely at odds with the OT stories until sometime after the time of Solomon; we obviously can't prove that something didn't happen, but we can establish that the context of the genocide stories does not fit with the historical context of any plausible time at which they could have occurred.)
So what path to choose? Worship of a God whose supposedly inspired literature contains fictional atrocities, or look at the cold facts of evolution and say, “yes, this is where we came from, and we need to understand the legacy it has left us; but it no longer dictates our future”?