What does 1 Corinthians 12:20 mean?

Paul has just written that if we all chose our own job in the church based only on what sounded meaningful or exciting or important to us, the church might cease to exist. A church made up of people who refuse to perform any task except those associated with being the pastor, for example, would not be a "church." This is in the same way that a body made up entirely of elbows would not be a "body."

Bodies that survive, thrive, and accomplish their purpose have many and varied parts while still being just one body. Churches that accomplish their purpose have many and varied people serving different functions assigned to them through the gifts of the Spirit while still being just one church. Not every spiritual gift is equally glamorous in the eyes of the world. Not every task in a church is equally prestigious in the eyes of the world. But churches need people to fulfill those other roles, just as much as the body needs all those members to serve their purpose. They are all part of the same Spirit and need to work together for that reason.