Peanut butter definitely is. Even if you make it home-made you need to add some sort of oil to get the persistent creamy texture, but it naturally separates. To get that permanent creaminess you get from the store it's going to have various sorts of chemical additives - emulsifiers, stabilizers, etc. You also generally want to add some sort of a sweetener. I use honey, but with store bought stuff you're looking at all sorts of stuff including e.g. high fructose corn syrup.

By contrast cheese is completely natural outside of a few exceptions like American cheese. You take milk, add something to curdle it like an acid (e.g. vinegar) or rennet - an enzyme obtained from the stomach of young calves, separate the coagulated stuff, salt it, dry it, age it - you now have cheese. Ricotta can even be made straight from raw milk with no additives. Cheese's long shelf life is natural.