Poor analogy. The "man who was directly appointed by the son" was not present when the "johnny-come-lately" came on the scene.
The core issue is what you place your faith in: the Scriptures themselves or the earthly institution that claims to have a monopoly on truth.
Did Christ or did He not choose Peter to be His representative? Did He or did He not state Peter would be the rock upon which His church will be built? Did He or did He not state that which Peter binds on Earth, will also be bound in Heaven?
Let me be kind and refer to Saul, not as a fraud or as a tool of Satan to divide the early church but as a sincere individual who believed he experienced a vision of Jesus. How does Saul differ from Joseph Smith? Perhaps mohammed?
That is the failure of the protestants. They would mock saints, the Virgin Mary and ritual yet accept, willingly and blindly, the gospels of monarchs, disgruntled clergy and executioners. They mock relics and the Rosary but worship the Bible. There is the Church, the appointed heir of Christ, then there is pretend Christianity.