The simple fact is that the Scriptures did not fall from heaven but are words written in paper by men and are interpreted by other men. It is only by accepting the authority of men that we know what is Scripture, and we only understand it if others tell us what the words mean.
I myself have made it clear the Scriptures did not fall from Heaven, but also that their inspiration is not established simply by man’s decree, including an “authoritative” one that came in 1546 by a 9 vote margin, but by the Divine attestation that accompanies the reception of the Scriptures in faith, (in regeneration) and the changes realized from believing it, and the manner of testimony of those who attest to such being Scripture.
The idea that it is “only by accepting the authority of men that we know what is Scripture”, is contrary to its means of manifesting that it is true, seen in the abundant praise of it within Scripture, and the testimony of its power. It was not by ratifying a collection that the body of of Scripture was essentially established, but by the unique and enduring quality of them which made enabled the ratification of what had become historically evident. The Scriptures have life, and beget the same, without which man’s decrees would have no little lasting effect, and widespread literacy of such would need to be compelled.
If left to Rome, the Bible would be a rather obscure book, as until long after the Reformation, Bible literacy for the masses was not a priority, and overall there has been relative little manifest hunger for personal study of it in her areas due to the deadness of her gospel and preaching.
As for “we ONLY understand it if others tell us what the words mean”, that is a mark of the natural man, not the regenerate, (1Cor. 2:14,15) and infers that even the teachers of the word are given little or no personal illumination of the meaning of Scriptures. I would recommend you read some of Matthew Henry’s complete commentary for an example of the degree of practical application that can be gleaned from the Scriptures.
By studying books Daniel understood the time of the captivity prophesied by Jeremiah, (Dan 9:2) Israel was told “Seek ye out of the book of the LORD, and read” (Isa. 34:16) for prophetic proof, Jesus told the Jews “Search the scriptures” for proof of His Messiahship, and again, the noble but common Bereans examined the apostolic preaching by the Scriptures. 1Jn. 2:27 also infers that essential truths were revealed to true believers, thus guarding them against seducers who supposed they alone had insight into the Scriptures.
Of course, those who are given the gift of teaching may be given more light, and as God has made the members of the body interdependent, so believers need each other to properly grow in the grace and knowledge of God, and likeness of Christ. (1Cor. 12; Eph. 4)
However, as much as Rome would like to eliminate the inescapable problem of appealing to private judgment, which the apostles did, (2Cor. 4:2; Acts 17:2; 28:23) she cannot, as even assenting unto Rome as the only infallible interpreter of Scripture obliges private judgment.
Moreover, even Rome’s (few) infallibly defined teaching requires interpretation. Define “unanimous consent of the Fathers, which is a basis for certain doctrines of Trent (1546-1562) and Vatican I (1870) which lacks such consent, and so apologists render a more liberal interpretation, contrary to some R.C. authorities. (http://www.christiantruth.com/livingtradition.html) Even what constitutes infallibly defined teaching is not so defined as to prevent some controversy as to what this all includes.
In addition, 2Pt. 1:20, which is often invoked by R.C. apologists as disallowing the validity of practicing Acts 17:11, is an example of “wresting” a text, warned of in 2Pt. 3:16, as the verse is not speaking of interpreting Scripture, but of the manner by which Scripture was written. And thus the prophecy of the scripture is in contras with “cunningly devised fables”, of which type Rome has sometimes used, including the Donation of Constantine, the Liber Pontificalis, parts of the Thesaurus of Greek Fathers or Thesaurus Graecorum Patrum, and the most notorious Pseudo–Isidorian Decretals, the principles of which the renowned R.C. historian Johann Joseph Ignaz von Döllinger said “eventually revolutionized the whole constitution of the Church, and introduced a new system in place of the old—on that point there can be no controversy among candid historians.” (Johann Joseph Ignaz von Döllinger, The Pope and the Council (Boston: Roberts, 1870), pp. 76-77, 79, 115-116).
The papacy is the ecclesiastical version of “give us a king” (1Sam. 8:6) but in total, the implicit trust Rome requires of her, and which multitudes willingly give her, is neither warranted by Scripture or history, and will be eternally tragic for those who so rely on her.