yep, that's it... the little flap at the end creates high pressure under the wing which creates positive lift
modern supercritical airfoils aren't designed with such a sharp trailing edge
it has to operate at a higher AOA at low speeds to develop the same amount of lift when compared to conventional wings on the same aircraft, but at high speeds, it is much more efficient. I'm going to hold off delving into the reasons for the sake of brevity.
When examining this airfoil, remember that the NACA 2412 on your cessna doesn't account for effects outside the realm of an ideal gas. Fluids act differently in the transonic realm of compressability. Normal thinking does not apply to the shape of supercritical airfoils, even if you think you have a perfect grasp of the writings of newton and bernoulli. You may think it looks a lot like a symmetric airfoil or an asym that develops negative lift from its camber; but it certainly doesn't act like either at high speeds