I'm guessing any group of humanity will naturally form hierarchies. Seems like part of human nature.
Any group of humans will naturally form social relations. Some of these relations will be power-responsibility relations, where people trade responsibilities to do things which maintain the society in exchange for the power to choose how the things are done. This does not entail hierarchy, because it does not entail rootedness; there need not be any single person nor group of people who hold ultimate power and responsibility.
Interestingly, you know what does naturally form hierarchies? Capitalist markets, especially those which alienate laborers from the profits of labor. It is straightforward maths to show that markets tend to accumulate wealth in a few lucky individuals, and that wealth alone can be used to manipulate markets arbitrarily.