The rulers of the Inca civilization were members of royal dynasties or families. The emperor was called Inca. No other people really were called Inca, but over time this term came to mean the society in general. The emperors were also called the Sapa Inca. The high priest, governors, and generals were important members of the royal council.
Most members of the royal councils were family members. The emperors almost always married their own sisters. The emperor would choose a successor to the throne from among his many sons. Generally, the oldest first born son would become the next emperor. The emperor also had a council of nobles which served him during his whole reign. He would consult the high priest, who was also a sibling or uncle, for help with his problems. Of course he also talked to the generals to develop war plans. The generals were most likely to be a relative or good friend.
When the Inca armies conquered other ruling cities, they didn't kill the local rulers. Instead they let them rule as long as they followed Inca rules, didn't rebel, paid taxes, and kept the storehouses full.
The tax requirements were high. Women were expected to weave a certain amount of cloth, while men had to mine or serve in the army. Taxes were expected to be paid by commoners. If the commoners didn't have money, they'd pay with service on state projects or make items to sell such as thread or hand-woven cloaks. People could also pay the government by giving a portion of their yearly crop to the collectors for storehouses instead.