King lords vassal's knights peasants and serfs is this the ranking of people in medieval times?

In secular society, the order was:

• Royalty at the top
• Nobility
• Free people, including merchants, tradesmen, and so on
• Serfs
• and sometimes there were slaves

Knights, who were usually considered to be the lowest rank of nobility.

Peasants included freemen, serfs and slaves. Freemen were independent farmers. Serfs were dependents of nobles or landed gentry, to whom they owed allegiance; serfs were not entirely free, but were not slaves either. Most countries did not have slaves.