Jesus commissioned his apostles to be his witnesses. There is a difference between them and the church today. They have met and seen Jesus with their own eyes. An exception is the apostle Paul, but he had his own revelation of the risen Lord.
The church today remains a witness of the gospel of Jesus Christ, though of course not an eyewitness to his resurrection.
8 But you will receive power when the Holy Spirit has come upon you, and you will be my witnesses in Jerusalem and in all Judea and Samaria, and to the end of the earth.”