What humbles you?
The amazing complexity of my body, or of a single cell.
The mechanisms of biochemistry.
The night sky, and contemplating the enormous distances and energies involved in those tiny points of light.
The fact of my consciousness, derived by a series of recursive processes of evolution by natural selection across several different domains.
Other people, and how they respond to the trials of life.
Infinity, Mandelbrot sets, and a host of other mathematical constructs.
The vastness of time of space.