That is quite the dedication someone put into finding out God's killings. What if that effort was used to feed the starving instead? probably be a better use of time.
It's no more a waste of time than, say, someone cataloging miracles, or other religious stuff.
I'm not dodging by any means, just pointing out that it seems odd for someone who thinks God is fictional to analyze it to that extent.
And how much time and effort have people put into analyzing the motivations of characters in Shakespearean plays? People can and do spend huge amounts of effort on stuff that doesn't exist and/or is fictional.
Now, why did God kill that many people? Because He felt they were deserving of it because they refused to obey His commands. If God allowed those people to live, they would have slaughtered the believers. Of course, we can not do that at all. We do not have that authority. Only God does.
In case you haven't noticed, this is pretty much the
rationale every "true believer" follower uses to justify their own particular ruler's actions. At least you recognize that no human can be trusted with that level of authority, unlike many people. But what you need to recognize is that the reasoning that leads you to argue that humans shouldn't have it also would apply to gods. This has nothing to do with whether gods are real or not, but with the truism, "absolute power corrupts absolutely". A being which has absolute power does not need to be responsible with it, because there is nothing that can hold them accountable, and no reason for them to ever learn to be accountable to begin with.
That's the real reason no human has that authority, because humans are automatically accountable to each other. There is no intrinsic property that makes a ruler immune to being shot or killed by one of their subjects. That's something we teach our children, most of the time, that actions have consequences and thus they need to be responsible with what they do. Now imagine a being who is the pinnacle of existence - nothing else can do anything to it, and thus it can do anything to everything else. When would it ever learn concepts such as decency, honesty, compassion, justice, all things we more or less take for granted? Why would it ever need to?
God is perfect. Therefore, anything He does is perfect, QED.
YOU may think it's wrong, but you are not perfect, so how can you know? it's quite a conundrum.
Actually, the only way something 'perfect' can remain perfect is by doing nothing. By definition, if something is perfect, then any change, no matter how slight, can only be for the worse. That means either your god can be perfect and not have ever done anything, or else your god is imperfect because he does things and therefore the things he does are also imperfect. It is impossible for your god to be perfect and do things and not be changed by doing those things.