Vegetarians are very noble in their respect for nature and life, but unfortunately, this doesn’t always correspond to good health. Not everyone can live well on a vegetarian diet. Just think of the Eskimos who spent millions of years evolving on a diet of 90% animal protein and fat.

You should also consider the work of Dr. Weston A. Price who studied many native cultures in the early 1930s before they were exposed to modern diets (mainly sugar and processed grains). He consistently found excellent health in these groups and many of them ate a significant amount of animal protein and fat. You can learn more about his work at the Weston A Price Foundation

You say that we learned to fly, build homes, and create clothing, but these arguments don’t correlate well with diet. We each have unique nutritional needs based on the environments that our ancestors spent millions of years evolving in. Some of us need a lot of meat, some of us can manage without any. It is what it is, and if we go against it, our health will deteriorate. As smart as we are, we’re not smart enough to outsmart nature and evolution.

I suggest you read “The Metabolic Typing Diet” by William Wolcott to get a better understanding of the different nutritional needs we each have. If you’d like, you can get started by reading the article I wrote on Metabolic Typing.

Even though I don’t agree with your take on humans being designed to be vegetarians, I can see that you’re motivated to make the world a better, more natural and healthier place. I think that’s great!