During the Noah's Ark episode, not only did God kill all the human beings, but all the animals that lived on land too, except for the two on the Ark.
Actually there were 2 of every unclean animal on the ark and 14 of every clean animal. There were not just two animals on the ark, nor 2 of every kind.
So, why was that? What did God have the animals.
Why did God cleanse the land? Have you read the parable? Because man was sinful and wicked in his ways, and had contaminated everything with his sin.
They had no original sin, considering that they had not eaten from the tree of Good/Evil when Yahweh told them not to, they couldn't be punished for not believing in Yahweh, simply because animals don't seem to need religion in their lives.
Animals are not spiritual beings, they have a soul as in the Hebrew word
nephesh, which means breath. As in they are alive, yet we have eternal spirits, which when we die ascends, whilst animals go back to the earth.
So, why did your God decide that he needed to murder all the animals as well as the humans?
Well first of all He is not
our God. He is God. Whether you believe He is or not, is irrespective. If you stand in the road and don't believe in traffic, it will still hit you. Doesn't make it any less real. If you acknowledge the fact that He killed all the animals and people as you do here, you need to acknowledge that He is God. I'm weary of this your God - my no God thing. He simply is God.
Secondly He did it because the land was rife with sin. Man was wicked and his heart was turned to evil from the moment he was born until the day he died, yet in this particular story, man had let sin consume him and it was throughout the land. So God cleansed the land and saved the one man who had fround grace in God, Noah and his family. From there he started over, and also promised not to do the same thing again.
To be honest, the answer is right in the Bible, I would suggest picking it up and giving it a read, try the NIV as it's written in pretty plain English.
Cheers!
Digit