I think you are mashing up different lessons:

- when you stand on the ground you are the subject of 2 forces: gravitational force m * g and the opposite reaction force of the ground surface, they cancel each other so you stand still

- when you free fall your acceleration is g and the gravitational force is m * g, this is according to Newton's 2nd law

when you hit the ground depending on your velocity and... deformation, the force of impact will be different because you will de-accelerate to 0 or even bounce back very quickly much faster than g. It's gonna be much stronger than g * m