"For as in one body we have many members, and the members do not all have the same function..."
Paul compares the church to the human body. As the human body is diverse and yet unified, so is the church. The church is diverse with many different members, yet unified in every member's commitment to the head, the Lord Jesus Christ. The body does what the head wills and desires.
The church is the body of Jesus Christ on earth. It is his hands, feet, eyes, mouth, ears and feet. Every Christian is a part of this body. Every member is significant with an important work to keep the body coordinated.
Some today deeply criticize the church. They think it's irrelevant to following Jesus. They are wrong. It's impossible to love Jesus and not love his Bride. Jesus died to give his bride life. How can you love Jesus and not that which he loves the most in this world? That for which he gave his life?
All Christ followers need to use their gifts to build up the body of Christ. It helps the body of Christ be coordinated. It keeps the church relevant in the world.
And as the church serves a broken world, the world sees a living, vital, relevant Jesus.