Old Testament: Genesis Chapter 9. Man is first given permission by God to eat animals after the flood.
New Testament: Jesus Himself eats fish, Jesus feeds 5000 bread and fish. Jesus never condemned Peter for being a fisherman. Jesus never condemned anyone for eating animals, and it was going on all over the places where He was. There were instructions from God on how to kill an animal so that it suffered minimal pain and went unconscious.
Those are my best reasons for it being ethically allowed. Do we revel in it? I don’t. But right now, until the world is restored the way it is supposed to be by Christ, we are able and for nutritional needs, generally need to have meat as part of our diets. I look forward to the day nothing ever has to die again, but I am grateful we have animals that we are able to eat. I am also grateful we can be kind to them while they are alive, and I am grateful for the animals I have as pets that I would never eat.
God’s even a fan of veal by way of Christ’s parable of the Prodigal Son and the father ordering the fatted calf to be slaughtered in celebration of his son’s return.