Step 1 of 10. Newborns' cries tell people they have needs. They will soon know words and be able to identify and ask for what they need or want.
Step 2 of 10. Kid's brains are developing and by about two they use the word "No" to say they are becoming individuals. It's much like voting.
Step 3 of 10. Three year olds ask questions. Endlessly, it may seem. Informed, they become more powerful.
Step 4 of 10. Five year olds want rights no one has given them, saying they want to button their own coats or tie their own shoes. With new abilities, they become more powerful.
Enough mystery. I was eleven when a baby sister started these steps. Three years later a baby brother started them. Ma and Pa Nature put the two on this path and as their brains developed they made democracy where they were. Decades passed and I was up my ears in politics before I realized what they were doing.
No one knows when early humans stopped obeying the alpha males in their tribes and started making decisions in groups. It was millennia ago and their only model was what children and young people did.
The ancient Sumerians did it. The alpha males in their city-states went to councils and asked permission to go to war. The councils sometimes refused the alpha males' requests.
In another thusand years the ancient Greeks did it and made decisions their armies obeyed. The ancient Persians did it, and to avoid groupthink they got drunk and and reconsidered what they had decided.