It's a combination of the forces - Bernoulli principle, Newton (angle of attack), etc.

As far as Bernoulli goes, it's been proven (at UND and others) that there is no motive force that 'makes the air molecules meet' at the trailing edge. They don't meet back up, so pressure differential alone can't acount for it all. Likewise, angle of attack can't do it all either. No one theory explains it all, but a combination does.

Lots of things contribute or detract from lift. Speed, angle of attack, airfoil shape, aspect ratio, laminar flow, slats, flaps, spoilers, flow devices like vortex generators and fences, etc. Change just one, and you've made a difference. Change two or more, and it gets complicated fast.

I've been teaching full-scale students for a number of years, and I like to keep things simple. They're trying to learn enough not to crash, not pass an engineering exam.