Why does our Stomach not Digest itself?

It's because our digestive tract has a protective layer made with mucus and bicarbonate, similar stuff found in your throat. It protects itself from the digestive juice (HCl), and digestive enzymes by not letting it penetrate through the protective layer. In case it gets through the digestive tract secretes a new layer.

The only way I can answer this that my thinking is that raw does not like raw.

It's the wonders of our creation. And that's the essence in itself.

if you don't eat food then it will defiantly start to eat up your stomach and then that is what is called ULCER.

This is like asking why the snake was not poisoned when they swallow the venom that they spit out. My guess is that, the snake is immune to the poison just like the stomach has a lining that prevent itself from being digested.

we do not brain of animal ,animal do not cook food and do not have varity of diff food ,god has made them like that ,hence friend u enjoy ,what u are ?