When the seat belt is properly fastened, it can apply most of the stopping force to the chest cavity and pelvis, which are relatively strong.
Because the seat belt spans a wider part of the body, the force will not be concentrated in a small area, so it will not cause excessive damage. In addition, the material used in the seat belt is much softer than the dashboard or windshield. It can be stretched slightly, which means that the stopping process will not be too sudden. However, the seat belt should not be stretched too long, otherwise you may hit the steering wheel or side window. The seat belt only allows you to move forward slightly.
