It may appear trivial, but thinking about it like a bunch of bullets bouncing off the wing on the bottom (the "particle regime") does not explain why it deflects air (the "fluid regime").
A fluid is governed by fundamentally different physics than a bunch of particles, so just because a bunch of particles hitting an inclined plane also would generate lift does not explain why air hitting the same plane does.
For example, in the particle analog, the upper surface of the wing is totally immaterial. You could make it look however you want without affecting the generated lift. In reality, the amount of lift generated is much more sensitive to what happens on the upper surface than on the bottom.
A fluid is governed by fundamentally different physics than a bunch of particles, so just because a bunch of particles hitting an inclined plane also would generate lift does not explain why air hitting the same plane does.
For example, in the particle analog, the upper surface of the wing is totally immaterial. You could make it look however you want without affecting the generated lift. In reality, the amount of lift generated is much more sensitive to what happens on the upper surface than on the bottom.