I suppose with our higher intellect and moral code than all kwnown animals we should find some way to get along without killing animals for food.
But equally, we'd then have to kill more plants. Just because plants are more different to us than other animals, we seem to treat them very badly. They're still living things, so who are we to exact such a dire existance upon them?
So, in my view, why not spread the damage across both types of living thing?
Indeed, without our omnivorus nature, many animals and plants would simply not exist. I suppose Cows still would, as people would probably still drink milk. But chickens? All gone. Can't pluck them for feathers, as we don't use them anymore, and its rather painful and unproductive, can't kill them for meat, and definately can't eat eggs; they're little baby chickens.
If there is some devine power that created us and didn't want us to eat other animals, surely they would have made us herbivores? And if the eventual abstinence of meat was a test of our divinity, we've either failed already, or we still have many centuries to go.
In the here and now, I'm a meat eater (and plant eater) as that is what my body has evolved to sustain itself on, and it provides the simpliest and easiest way of keeping up all my nutrient levels.