The Pope and his church were the highest in the class system. People went to worship God at the church, and the Pope could talk to people about the church.
Kings and Queens were about at the same class system as the Pope, but the Pope was more important because he was the head of the Church.
A Lord was someone who had land, and he gave chunks of it to peasants and they would work on the land. The Lord was a rich person from the land. Lords were below Kings and Queens, but they were still pretty high in the class system.
Knights were hired by Lords to protect the Manor.
Merchants were people who went to places and sold goods.
Peasants were people who worked all day long in the fields. They barely had any rights, and they were very, very poor. They were low in the system because they were so poor.