“Molars are designed for grinding all food (try eating a steak without using your molars)”
Sure, but we don’t have either the molars or the general tooth structure of a carnivore. Judging by our teeth, we are obviously omnivores, which means we have evolved (or been designed, if you prefer) to eat grain. It’s ridiculous to assert that our jaws and teeth had the time to adapt to eating it, but our digestive systems haven’t.
Again if you more information look it up yourself. Vegetables are food too.