It isn't necessary to do all this deep diving into anatomy to "own" vegans. The anthropology is very clear that humans evolved eating mainly animals, specifically meat. Since all species evolve to their environment and food supply (not the other way around) it is trivial to understand that our optimal food will be the closest thing to those evolutionary foods.
Vegans hate this reasoning which is why they try so hard to lie about anthropology.
Not only did humans evolve eating meat, but a significant amount of evolution took place after the invention of fire, which improves the ability to absorb nutrients from both meat and many plants. Our gut isn't ideally set up for meat but neither is it ideal for digesting plant matter, it splits the difference.
Also, our guts are full of bacteria, and anything we eat rots to some extent before we get it out.
Which BTW is why fermented food us universally good for humans to eat and drink.
Essentially they are external digestion.
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