Emergence
The world's complexity often resolves into higher-level simplicity. We can predict how long water will take to boil without understanding the interactions of its trillions of atoms—we need only a few measurable quantities like mass and heat.
This phenomenon, called emergence, creates a layer of reality that can be explained in terms of itself. "Emergent phenomena are essential to the explicability of the world," David Deutsch notes.
Long before scientific understanding, humans controlled nature through rules of thumb about high-level regularities like fire and rocks. Even earlier, genes encoded knowledge about emergent phenomena.
Emergence creates the scaffolding that allows knowledge to develop incrementally—each scientific theory successfully explains a "layer" of phenomena, even if imperfectly. This is why emergence represents "another beginning of infinity": it makes the world comprehensible not despite its complexity, but because of how that complexity organizes itself into patterns we can grasp.