The head of government in the Inca Empire was the Sapa Inca. The Sapa Inca was a god. He was not a monarch, nor an emperor, nor a king. To the Inca people, he was an actual god. He was sacred. The Inca believed he was descended from the most important of the many Inca gods - the sun god Inti. The Sapa Inca represented Inti on earth. Government and religion were totally intertwined in the Inca Empire, because the head of government was a god.
The Spanish gave him the name "sapa". They perceived him as the emperor or the king, because that was their background; that's what they were familiar with for the person in charge of government. The Sapa Inca was called Apu by the Inca people, which means divinity. We're going to call him the Sapa Inca because the Spanish name stuck and that's what he is referred to today, except of course by scholars. But it's an important distinction and the reason the people did not revolt. The Inca people believed if they tried to overthrow the Sapa Inca, they might anger the sun god Inti and be punished by losing the sun. You can imagine how powerful that made the Sapa Inca.
The Sapa Inca owned everything. He ruled everything. He made all the laws. He was all powerful. There were only two ruling families during the Inca Empire. Both ruling families were considered decedents of the sun god Inti. Whichever was in power, each Sapa Inca put his relatives, along with the nobles, in positions of power, to help him rule the Inca empire. Each Sapa Inca had four top advisors, who make sure the relatives and nobles did the work they were assigned to do.
When a new law was put in place by the Sapa Inca, word went down the line from the top officials until it reached the bottom officials, and from there to the common people. Since the common people had no say in government, that was the law until a new law came down.
This system worked very well for the ruling families, and the Inca population grew to about 12 million people, nearly all of whom were the commoners or peasants.