@SWORD of GOD,
The Quran is noble because it's the exact words of Allah (God), the most Noble, revealed by Him to His final messenger, Muhammad (PBUH).
"Nay! This is a Glorious Quran, (Inscribed) in Al-Lauh Al-Mahfuz (The Preserved Tablet)!" [Quran 85: 21-22]
Whenever Prophet Muhammad (PBUH) receives revelation as partial verses in Arabic, He would immediately have his writers write these verses on the leaves, woods, bones or parchamen papers and these parts would be kept well in containers.
The angel Gabriel would instruct Prophet Muhammad (PBUH) about what chapters will these verses to be listed under. Then, His companions would copy their own copies from this main copy. At the same time, since reading from Quran in daily prayer was required, many companions of prophet would memorize all the verses that were sent, the others would memorize some parts of it. Prophet Muhammad (PBUH) had also appointed over 40 writers among His companions. These companions were also educated about the order and the meaning of Quran. Prophet Muhammad (PBUH) would make it clear about the order of chapters and the organization of Quran.
Shortly after Quran was completed in the last year of Prophet Muhammad (PBUH) in the life, the Angel Gabriel and He went over all the verses and chapters by reciting Quran together twice. About one year later Messenger Muhammad (PBUH) died, Omar (may Allah bless him) suggested Abu Bakr (may Allah bless him) (the first khaliphet and the most important companion of prophet) to collect all the writings as whole book. Zeyd bin Sabit, the leading writer of the Prophet (pbuh) supervised and guided the collection work. All copies that belonged to companions were collected and compared. After making three times sure to build a perfect copy, it was kept as a model manuscript for all who wants to copy Quran down. . Organization, order and the name of the chapters and the order of all verses, everything was done in the way that Prophet Muhammad (PBUH) instructed.
In Quran, God declares that Quran can never be changed:
'Nay! IThis is a glorious Quran...(Inscribed) in tablet Preserved" (Chapter 85 : Verses:21-22)
After Abu Bakr died two years later than Prophet Muhammad (PBUH), Omar was suggested to become the second khalife. After over twenty years of leadership of Muslims, Omar died and Othman bin Affan became the third noble khalife. During Omar's time, many people and country from three continent had been introduced to Islam , joining the mainstream and increasing the Muslim population by hundreds of times. Of course, language and the alphabets of these different nations and accents of other Arabic speaking countries were different from each other.
To be able to preserve a fully correct copy, Othman (May Allah bless Him) consulted the other companions and several book-copies of Quran made and sent over different countries of the world. All other copies that were written on other dialects other then Makkan dialect and writing style of Arabic were burned not to cause confusion. Today, many important libraries have these very original copy. All the copies in the world are the same exact version of these initial copies, letter to letter.
Moreover, the copy in Topkapi Palace in Istanbul was the personal copy of Khalife Othman (M.A.B.H). Indeed, he was murdered while reading on his Quran. You can see the page with the marks of blood on it.
About the earlier scriptures, Islam considers the corruption of the Torah and New Testemant in both the text and the meaning. Although right now we have very later versions of Bible, there are some earlier copies that we have heard the Church has forbidden to publish. The reasons are quite interesting and supports what Quran teaches and says about the earlier scriptures.
