“...Could be not all apostles “got it”(fully)..”
With all due respect, I believe you might be misinterpreting the four different aspects of the life of Christ recorded in the four gospels.
John did not “get it” more clearly than did Matthew, Mark and Luke. While the gospels have many similarities and record some of the same events, each is geared to a specific aspect of His life. All four generally cover the four great points of the gospels - the presentation of the King, the declaration of His Kingdom, the rejection of the King and the rejection of His Kingdom - but from different perspectives.
Matthew emphasizes the presentation of Christ as Jehovah’s King which is why his gospel starts with “The book of the generation of Jesus Christ...” and continues with the royal genealogy from Abraham thru David and on down the line to Christ. Many sections peculiar to this gospel are mostly related to the King and the Kingdom.
Mark emphasizes Christ as Jehovah’s Servant as noted, for example, by the fact that in the other gospels Christ is addressed by individuals as “Lord” many times yet only twice (both mistranslations in KJ) in Mark.
Luke emphasizes Christ as Jehovah’s perfect Man which is why, for example, it details the pre-natal section of Christ’s life. This includes the best biblical account of why a person is considered by God to be alive in the womb (when the fetus now known as John the Baptist acknowledges the recently conceived Christ as pregnant Mary visits her preggo cousion Elisabeth) rather than a simple ‘non-viable tissue mass’ as liberal abortion-lovers would claim. It is also why Luke is the one to present the human genealogy from Christ back to Adam.
John emphasizes Christ as Jehovah Himself, Divine. To finish your quote of John 1:1, “In the beginning was the Word, and the Word was with God, and the Word was God.” Christ is the living Word (Logos in the ancient Greek) which is why it is capped. Also, speaking of metaphors, I can’t help but think of some of the hardcore EVOs when I continue a few verses down to read “And the light shineth in darkness; and the darkness comprehended it not.”
Obviously, the bible is full of metaphor, figures of speech, types, analogies, symbolism, etc. But detailed knowledge of the OT and various prophesies referencing the different aspects of “The Branch” (Christ) are required to fully understand the uniqueness of the four gospels and their overall harmony.
Also, Paul, as I’m sure you know was not an apostle or even a disciple while Christ walked the Earth in the flesh. He was rather violently chosen later by the risen and ascended Christ to perform a three-fold ministry - to the Jew, to the Gentile and to the authorities of his time. Before that, while the other apostles were personally witnessing the life of Christ, Paul was a zealous Jew and a sworn and effective enemy of the Lord Jesus.
The "apostles" CHOSE Mattias to replace Judas.. which was a mistake.. The Holy Spirit chose Saul to be an Apostle.. as Paul said he did.. For it was the Holy Spirits authority to choose an apostle.. not man.. A tree is known by its fruit..