> We can digest just about any meat there is. We cannot digest any plant. Try eating a tree branch and see how far you get.

While I'd absolutely accept that wild humans are omnivores, your first statement here is false — there are many kinds of animal flesh and organs (tree branches are more like bones than anything else) that are bad for humans, and can even be lethal. Even some meats which are safe in moderation can cause harm if they're the only one being consumed.

But I'd also argue that it's important that we're not wild any more. We may not be able to eat wood, but we can burn it to create an external second stomach in the process we call "cooking".

Now I think about it, it's also important that the environment is, by our actions, radically different to the one we evolved for. Both plants and animals have been changed by many generations of selective breeding to be better suited to our dietary desires. (And other desires, but those don't matter for this topic).