If effective complexity is to be understand as a system moving in a structured yet unpredictable way, the slime mold can be a fine example. The slime mold is a single celled organism that will continuously expand itself until it reaches food nearby, at which point it will contract until it exists in the shortest path between itself and food. It has no control over the food position, but will follow the same logical procedure when it finds the food.
I think about The Problem Of Uniqueness quite often. Instagram is now full of simple effects on typography, or looping gifs of shape illusions. Even more complex generative art tends to follow much of the same structure. I do think that there are moments with which artists can express uniqueness, even in a space where it seems everyone is playing the same hand. Take for instance the generative artist Shane, who has donemanyplays on the idea of a tunnel, or turned a truchet pattern into a structure, or sculpture.