Is it accurate to say that Jesus was not the first Christian, since he is the Christ, and Christians are followers of Christ?
No, Jesus was not the first Christian. Strictly speaking, a Christian is one who receives Christian baptism and thus is a disciple or follower of Christ (Matt. 28:18-20). As eternal God, Jesus had no need of Christian baptism and no need to be anyone’s disciples. Jesus received the baptism of John only to “fulfill all righteousness” (Matt. 3:15; see also 3:13-17). By doing so, Jesus identifies with sinners and aligns himself with God’s plan, which includes performing Old Covenant regulations to fulfill and perfect them in the New Covenant. (For more on this passage, see the Ignatius Catholic Study Bible New Testament).
Jesus is “the way and the truth and the life” (John 14:6). As his disciples, we follow him in the fullness of the Faith in his one Catholic Church.