Gorillas have an enormous hind gut with a microbiome capable of digesting plant material to release the fatty acids in for example cellulose. We, as humans, do not have this facility. Just compare our anatomies - we have short guts because we eat meat and fish - we have outsourced our primary food production to the herbivores.
I do not know where you are getting your ideas, but I think you are mistaken in your beliefs and nothing you say provides any evidence in support of your contention.