From what I understand, the first kings started off as feudal land owners. Knights served as their enforcers and common people paid to live in the land.

How was this a sustainable group dynamic?

Why did people consider kings claim to land/right to give orders legitimate?

Technically, the only people with any real power in this situation would be the knights, with their collective military strength, and the peasants, with their collective ability to work the land. Why all these groups hand over power toward one individual?

Early kings might have maintained their authority just by being the toughest member of whatever group they were heading, but kings' authority generally seems to last even when it is handed down through heredity rather than through merit. Why did people follow them?

If anyone could shed some light on this, I'd be appreciative. I honestly don't get it.