One thing to add is that you can push air down in numerous ways but some ways are less efficient. So an 45degree angled blade absolutely will give you lift but

One thing to add is that you can push air down in numerous ways but some ways are less efficient. So an 45degree angled blade absolutely will give you lift but a tapered aerofoil will do the same with less energy spent pushing the air in unwanted directions (specifically fewer swirling vortexes immediately behind the wing causing drag). So yes push air down to stay up. Don't push air sideways or in circles. The aerofoil shape and the equations that simplify the 'don't push air the wrong way' into a simple term of drag are all about doing this.