Excellent illustration. The same reasoning applies on the universal level, ie, to the universe.
Natural processes formed the same way that the river formed, they are things that worked successfully. Likely, the processes that you refer to came into existence coinsiding w the birth of the universe. We could say that it was a successful universe. We don't know how many aborted universes, so to speak, there were, the unsuccessful ones, because there were not the right processes or laws coming into existence along w them.
A look at the different kinds of stars and all the different processes in which they are involved also demonstrate success and failure by natura;l processes. Many of them do not work, ie, stars explode without ever getting nice planets orbiting them. Many gas balls never make it to stardom. Many other examples are there to be seen.
As well, our own solar system and how it was formed show the same principles as the river illustration. Basically it startted from a gas ball and a bunch of asteroids, rock chunks and some comets. Out of this chaos emerged the various planets, the oort cloud, sun, etc. Mars was close, but no prize. Earth, of course, did better. But again, it has been shown that natural processes did eveything to bring the earth to where it is today.