[askvictor]

Generally you're either killing _all_ of the bacteria the sealing the product to prevent new ones entering, or creating an environment that's too hostile for them to live (environments high in salt, sugar, acid, or fat, or low in moisture, all make achieve this)

Also, our stomach is full of acid, the purpose of which is to kill bacteria. Later on, in the intestine, you have a colony of microbes.

Pickled or fermented food is very healthy, and shelf stable. We've been doing that for millenia to preserve food.

It's not as simple as you suggest.