We are very close to dogs in many ways. Most medical research has been done on dogs because of this commonality. The God you worship is omnipotent and omniscient. As such this Being has the ability to control without killing. All things are possible for this Being.
The fact that the God of the OT chose genocide and the unbelievable cruelty of drowning almost all living creatures on the earth in a great flood, indicates to me that this Being is not worthy of respect let alone worship.
Now if you want to say that the OT was part history and part metaphor; that your God is Jesus Christ and not a homicidal maniac, then that is a concept that I respect. I can understand the worship of the gentle Jesus who loved all, even the sinner.
If God did not have total dominion over his creation and could not do with it as He pleased then He would not be God. We are not in a position to judge God. That having been said I would like you to consider the following:
The pagan people’s that lived in ancient history were extremely course and primitive. They worhipped things made by their own hands, or animals, or other things of nature. Some of them, such as Pharoah and others, set themselves up as gods. Sacrifices on the part of pagans were incredibly cruel, ungodly, and debased. It is difficult for modern man to fathom just how bad some of these things were.
The evil and sinfullness associated with pagan practices and beliefs are antithetical to God and truth. Pagan practices could not be easily overcome. God gave pagan peoples plenty of opportunity. Moreover, He gave them the example of the chosen people. In some cases pagans converted to Judaism, but most by choice remained steeped in the darkness of their evil ways.
Even the chosen people would fall back into pagan worship. The only thing that many of these peoples understood was power. They believed that their pagan gods would lead them in battle to conquer their neighbors. They were ruthless and unmerciful in dealing with their neighbors. They could only be convinced by the utter defeat of both their armies and their pagan gods.
You seem to think that God could have dealt with them differently. This might be true, but it is an assumption that should not be made. No one can counsel the Creator, and no one can know what He knows. Our wisdom is like straw in comparison. We can only attempt to understand. It could be that if God had done things differently, then the gift of free will may have have been compromised or destroyed. The gift of free will is part of our humanity. It is also abundantly clear that man has exercised free will for good and for evil.
You would not feel the least bit guilty about destroying a nest of killer bees, a nest of termites destroying your house, or defending your family against a pack of wild dogs. The killer bees, the termites, and the wild dogs have no rights and have no say so over how you might choose to dispose of them. If they had the ability to think as you do, they may not think that your methods were proper or merciful even though you do.
Finally, please be aware that you cannot apply your personal human standards in dealing with other human beings, be they right or wrong, to the Creator. You cannot logically do this any more than a termite can apply its standards to you.
Likewise, you cannot think of ancient societies based on your modern day western societal norms. Most of us have little or no personal experience with the horrible things that some men perpetrate against others.
I hope this is begins to help at least a little.