How was the Qur'an, the Final Word of God, Acquired?

It is a well-known historic fact that every religious Scripture revealed before the Holy Qur'an suffered alterations, additions and subtractions; some have even disappeared altogether.
Leaving aside the ancient ones, take for instance the case of Jesus, the most recent of the Apostles of God before the Holy Prophet Muhammad. What is available today is a collection of mere stories told by different persons at different times based upon often contradictory records. And even this has undergone revision, with various translations of the text, hailed by some and contested by others; for example the Douai Bible of the Catholic Church, the King James Version of the Protestant Churches and the Diaglott of the Watchtower Society, etc. This destructive activity by man was tolerated by the Almighty Providence while the Scriptures were being tampered with, awaiting the Final and All-Comprehensive revelation which was yet to be given to the human race. This was revealed to the Holy Prophet Muhammad, the Last of the Messengers and Warners from God. This Final Word of God, the Qur'an, was sent down with a challenging Under taking and assurance that none thereafter shall ever be able to tamper with it, meddle with it, as the Omnipotent Author of the Word and its Revealer Himself would take care of its Originality, Arrangement, Completeness and Security:
Verily, We have sent down the Reminder (the Qur'an), and verily We (Ourself) for it will certainly be the Guardian. (15:9)
On Us is its (Qur'an's) Compilation, its Recitation and its Explanation.
Before leaving this world, the Holy Prophet declared:
I leave among you Two great (very important) things, the Book of God and my Ahlul-Bait; should ye be attached to these Two, never, never shall ye go astray, and verily never, never shall these Two be separated from one another.
This Apostolic announcement clearly states that:
1 The Holy Qur'an was there in the form of a complete Book.
2 It was there in the hands of the people, for the Holy Prophet says, "I leave among (or in the midst of) you".
3 To avoid going astray, people should hold fast to both, the Qur'an and the Ahlul-Bait, and not to others.
4 The Ahlul-Bait will always be with the Qur'an, and the Qur'an in its original form and with its correct meanings will be only with the Holy Ahlul-Bait.
5 As the Holy Prophet says, these Two will never be separated from each other. As long as the Qur'an is there in this world, there will be one of the Ahlul-Bait (the Imam of the age).
The historic recital of the Qur'an by the severed head of Husain, the King of Martyrs, at Karbala, proved that a member of the Ahlul-Bait, even when killed, is the custodian of the Qur'an and can deliver it to the world.