Humans aren't herbivores
Killing animals and eating them may be immoral, but can we please stop claiming humans are "naturally" vegetarian? We're opportunistic omnivores, which probably has something to do with why vegans need to watch their diets carefully in order to have working blood cells.
Look at your teeth. Now back to me. NOW BACK TO YOUR TEETH. That's generalized dentition, and appears in classic omnivores. Look left. It's a chimpanzee, our nearest evolutionary relative. He's killing and eating a Colubus monkey, their most frequent prey. Look down. What's that in your gut? Oh that's right; it's a lack of a fermenting vat, efficient digestive enzymes for grasses, and inability to synthesize key vitamins and amino acids. Look again. THOSE DEFICIENCIES ARE NOW A COLONY OF SYMBIOTIC BACTERIA WHICH METABOLIZE ANIMAL TISSUES. I'm eating a horse.
I enjoy fruits and vegetables. I eat a lot of them. Probably more than most vegans. And don't get me started on how amazingly delicious (and good for you!) vegan food can be. But we really are omnivores—PETA's bad science to the contrary.
Please adapt your moral schema if necessary.