The Mandelbrot set is very complex, but is generated by an absurdly simple rule. There are many instances in math and physics where complex behavior is an emergent property of simple rules.

You're also confusing understanding with logical omniscience and omnipotence. I know all the rules of chess, but I do not know every fact those rules entail, and I do not know how to win every chess game. Even if I did know those things, certain moves are impossible even though I know everything about chess.