To answer the question and stay on topic: It seems very likely that Paul invented/manipulated Christianity.
Why? There were 12 (+) other Apostles.
Ignatius of Antioch, an early Father of the Church, lived around the late 1st and and early 2nd century. We have a good amount of his writings that he sent to various churches and individuals on his way to martyrdom.
His writings are thoroughly Catholic (and traditional Christian), expressing such things as Christ’s divinity, the atonement on the cross, the Virgin Birth, the Real Presence of Christ in the Eucharist, and the structure of church clergy/hierarchy.
Yet Ignatius is known to be influenced by Peter, whom he is a successor to in Antioch, and John, whom he heard preach.
“Ignatius, also called Theophorus, to the Church at Ephesus in Asia . . . predestined from eternity for a glory that is lasting and unchanging, united and chosen through true suffering by the will of the Father in Jesus Christ our God” (*Letter to the Ephesians *1 [A.D. 110]).
“For our God, Jesus Christ, was conceived by Mary in accord with God’s plan: of the seed of David, it is true, but also of the Holy Spirit” (ibid.,18:2).
“[T]o the Church beloved and enlightened after the love of Jesus Christ, our God, by the will of him that has willed everything which is” (*Letter to the Romans *1 [A.D. 110]).
“Take care to do all things in harmony with God, with the bishop presiding in the place of God, and with the presbyters in the place of the council of the apostles, and with the deacons, who are most dear to me, entrusted with the business of Jesus Christ, who was with the Father from the beginning and is at last made manifest” (ibid., 6:1).
“Take note of those who hold heterodox opinions on the grace of Jesus Christ which has come to us, and see how contrary their opinions are to the mind of God. . . . They abstain from the Eucharist and from prayer because they do not confess that the Eucharist is the flesh of our Savior Jesus Christ, flesh which suffered for our sins and which that Father, in his goodness, raised up again. They who deny the gift of God are perishing in their disputes” (*Letter to the Smyrnaeans *6:2–7:1 [A.D. 110]).