I created this example to see if i can explain how humans walk but I can't. If I'm correct, when we push the ground to move forward we apply a force with the opposite direction (backward). Let's name this force Fp (for push). Because of that force, a friction force is being applied to us with the opposite direction of Fp (forward). While |Fp| <= |Fsmax| , we don't move at all. At some point |Fp| > |Fsmax| so we should slide (move) backwards and then Fs will be Fk (kinematic Friction). Then why in the real word we move forward? Am I missing something here? Please consider that I'm new in Physics.