The two of the forces that airplane experiences are lift and drag. And the airplane experiences more lift as compared to the drag, due to its shape.
If the drag has been more than the lift, the aircraft would have gone backward and not forward and it would not be able to take off and move forward.
So this shows that an airplane will not move backward unless the drag (which the body of an aircraft resists) is more than the lift (provided by the wings of the airplane).