Qur'an is not contaminated

Uniquely, among all heavenly books, Qur'an was not contaminated and here is the evidence:
Qur'an preservation was not done by copying a chain a books in series way. It depended mainly of memorizing it by huge number of independent people chain who till now transfer it by memorizing and each one can not take a certificate that he/she memorized the Qur'an and can review other people memorization except he/she has continuous chain till Prophet Mohammad, and by the way the book itself was written from brain of memorizing people with two witnesses for each single memorized verse that this verse is correct, and this happened (the writing process) few years after prophet Mohammad death.

When you know that piece of information about Qur'an, I can ask you a simple question, if the Qur'an was contaminated it would be contaminated not only from single point of memorizing chains, and hence it would generated (contamination process i mean) a huge versions of Qur'an and you would find the Islamic world is divided according to the version each group think it is the right. But this is not the case.So the first assumption is wrong.

Again I say proudly it is surely uncontaminated. BTW this method of licensing the memorizing people and transferring Qur'an is called in Arabic "Tawator" and it is unique.You can say also that the referencing method has emerged to world since Muslims have done it in Islamic religion, the only religion that have references for its book.Every memorizing one has a certificate including the names of his/her chain till reaching prophet Mohammad then God.