Yes and we know these things due to science. The problem is that you have only a glancing understanding of the science and are cherry picking ideas to support your preconceived conclusion while rejecting mountains of evidence to the contrary.

That is not how science works.

I would be much more amenable to accept some of your arguments as at least having a grain of truth if you demonstrated even a fundamental understanding of evolution and biology. The fact that you do not understand that humans are omnivores (this is not debatable) and we evolved to be that way over millions of years demonstrates that you either didn't pay attention in biology class or you have chosen at some point in your life to reject science and facts.