Over our planet dominates a huge air of the ocean. And the man pressed with a force of more than 15 tons. Imagine that you hit 3 of the truck - that's what this weight! But these "trucks" will never crush man. The reason is that the "air column" puts pressure on us not only from above and from all sides evenly. In addition, inside us too there is air. And this air is under the same pressure. The air pressure inside balances the pressure on the body from the outside. That is why we do not notice the pressure on your body.
In the process of evolution, living organisms have adapted to earth's atmospheric pressure, equal to about 1 kgf/cm2. Our inner pressure just equal to atmospheric. But, for example, deep-sea fish have adapted to a still higher pressure. If such a fish out of water, it "explodes", because the pressure inside is higher than the pressure of the atmosphere outside.