Hmm, I think you're missing my point. No matter how corrupt, evil and depraved humanity may have become, the animals themselves had done nothing wrong. They were innocent. They didn't deserve to suffer for OUR sins.
Yet God killed them in a truly horrifying and terrifying way. Virtually all of them, and for what? It appears to me there was no good reason whatsoever to slaughter so many billions of innocent lives. God could have killed the humans without harming a single animal, yet he chose not to. Why would a good God do such a thing?
I don't think this is a question that anyone should simply ignore because it speaks fundamentally to God's character. If there's not a clear, logical, obvious reason why God would behave in such a way...does he deserve our love? Does he deserve our worship?
I'm beginning to fear that the reason we're so evil is because we were indeed created in God's image....