Why didn't early people form governments?

Because they were too busy being cavemen

 After the birth of agriculture, once nomadic people began living in fixed locations. Of course with a surplus of food and stable living conditions, these people began to expand in numbers. his led to social stratification (or hierarchy); another factor that led to social stratification is having a large brain. With a larger brain than animals, early humans had a more matured dialect, and they were capable of cooperation. Anyways, social stratification started with the hunters/"farmers" on the bottom, skilled workers (pottery makers, spear makers, etc.), and then the few that governed others. If no one took the responsibility to lead the people, the people would be unorganized, and they would most likely clash with one another.