Walking and running are so much different from the primate mode of walking and running. As a matter of fact all the "technical" modes of movement are different from their "natural" counterparts. There are no fish with propellers or no birds with jet propulsion.
I was always perplexed with walking. I mean we are not pushing or pulling anything, but we are able to move horizontally. Until I watched a documentary, I had no idea what was the underlying principle. When I learned what the principle was I was filled with joy, and had to share this with you science loving readers.
It turns out that we are nothing but 2 inverted pendulums. Our body is the mass on the pendulum, and our legs are the rods. As we step, our feet function as the pivot of the pendulum. Figure 4 from this article was the best pictorial explanation I could find.
This fundamental difference between the modes of transport of the animals and the machines reinforces my understanding that evolution produces solutions that are just good enough to stay alive. Not more than that.