How does the relative wind on a propeller, strike the blade from behind (the non camber side)?
Plane moving forward plus blade moving down gives us a combined velocity vector, shown above in red.

Relative air(speed) is still coming from ahead—but this now no longer concerns the propeller as it has its own velocity vector.

Tilt your head (or check right image to avoid neck injury) and you'll see the blade's angle-of-attack. Remember, air (shown above in light blue) comes in from the direction opposite to the velocity vector.



Increase forward speed, velocity vector changes, angle-of-attack is now smaller, but the airfoil is also faster.