The outward appearance of anything in a nature or making any kind of change in our behavior or our bodies tends to seem overwhelmingly complex.
But remember this… Complexity arises from simple rules repeated (See Mandelbrot).
In nature, one only need to appreciate the branching of a tree. The simple rule of growth for a tree is to split one branch into two branches. Rinse and repeat. Over time, the result is what appears to be this incredibly complex structure reaching upward and spreading out in all directions.
When nature finds a simple rule that works, it uses it over and over. In humans, we actually use the same “tree” rule in regard to how we form the vast network of blood vessels in the body. One artery splits into two and so on to such a degree that direct blood flow is never more than 5 cells away from any one cell.
The dendrites emanating from your nerves to allow communication with other nerves follow this rule too. One branch splitting into two and so on. In fact, this process is called dendritic arborizaiton (arbor = tree).
The Parsimony Principle in regard to science tells us that the best explanation for any phenomenon is usually the simplest one based on the evidence. Complexity often hides the simple explanation.
Human movement follows simple rules.