Let's take a look at the Gospel/Church as it existed during Christ's time on Earth.
Hebrew 4: 10-15
10. He that descended is the same also that ascended up far above all heavens, that he might fill all things.)
11. And he gave some, apostles; and some, prophets; and some, evangelists; and some, pastors and teachers;
12. For the perfecting of the saints, for the work of the ministry, for the edifying of the body of Christ:
13. Till we all come in the unity of the faith, and of the knowledge of the Son of God, unto a perfect man, unto the measure of the stature of the fulness of Christ:
14. That we henceforth be no more children, tossed to and fro, and carried about with every wind of doctrine, by the sleight of men, and cunning craftiness, whereby they lie in wait to deceive;
15. But speaking the truth in love, may grow up into him in all things, which is the head, even Christ:
If Christ set up apostles, prophets, evangelists, teachers, and pastors to guide His church, do you think that is an important part of the "Original" Gospel?
I think that at the very least the presence of apostles and prophets must be important to the Gospel and were obviously had in the original Church.