Yes. The point of the airfoil shape is to make flying more efficient, i.e. the engine would need to generate much more power if the wings were flat slabs, but the plane could still fly given a big enough engine.*

*Assuming the "big engine" wasn't so heavy that it made flight impossible because of its weight.

It may be. Indeed how do helicopters even fly.

But the point is that Lean formalisation is a new bar for engineering and for physics and abstract math.