Are you going to eat meat? Just try to capture a wild animal with your bare hands and eat it raw, you will look ridiculous. This isn't a practical option without technology.
And even if you manage to capture it somehow or scavenge one that is already dead, there are tons of bacteria and diseases that you can get from raw meat since humans don't have the hydrochloric acid that carnivores do. Are you going to eat diary? Of course not, it is totally unnatural to eat another animals milk.
Legumes, beans, and grains although healthy, generally need to be cooked or otherwise prepared. They aren't edible raw. Similarly, many vegetables need to be cooked and they contain parts that are indigestible. Nuts often need to be cracked open.
On the other hand, fruits are just there on the tree ready for picking they don't need any special preparation - it should be completely obvious that this is the food of primitive people - our ancestors.
