Jesus was The Christ - the foretold Messiah.
He established the promised New Covenant, in His shed blood, and on the night before He submitted to crucifixion, He invited His followers to enter into that "covenant for a kingdom" - Luke 22:20. They became Christians by putting all their faith in Christ and following Him. Christ did not put faith in Himself and start following Himself.
As to His human nature, He was Jewish (via His Jewish mother, Mary). As to His divine nature, He is God - the Word who was in the beginning with God, who IS God, and who made everything that was made. John 1:1-14. That Word incarnated, becoming flesh. God is not a Christian. God is over and above everything in existence and He is the one who established Christianity as a continuation of His covenant dealings with sinful humanity.