Was this Verse real or an add-on? -S Turkman

There were only 17 people in Hijaz, who knew, how to read and write.
Amir MoAawiyah, Warqa bin Nofil (a former Jew), Abu Zar Ghaffaari were 3 of the ones, who are known to have written 'Wahi' (words of Allah relayed to Prophet Mohammad by Angel Gabriel).
When Qoraan was being compiled, it would have been rather easy if someone, who had memorized it, recited it and someone had written it down but no such person was found therefore, it was decided to collect written material.
When Written Material was being collected, a few Moslims had questions its authenticity because any of the permanent or part-time Wahi Writers could have written up some of it himself and turned it in. They had also said that "Material not written by the original Writers of Wahi should not be included because its probably a copy, not original and then who knows, if its genuine or fake", but they were ignored. .
.
There was no authority on Qoraan, who could decide, which Script was from Allah and which was not.
When Qoraan Compiling ended, there was a Verse in it saying, "Allah would guard Qoraan's genuineness Himself".
The Question is, how could Allah say this, when Qoraan did not exist in form of a compiled book in those days and its Scripts could have been changed, material it was written on could be soiled, spoiled or mutilated and Ink Erosion could have taken place?
The next question is, why had this Verse come, when Qoraan compilation had not yet started?
And then, final Question is,was this Verse real or an add-on?
Nobody knows but its still considered real authentication of Qoraan, when actually it remains a fact that there was nobody to authenticate the Material that was gathered and used to compile Qoraan. The Facts are in favor that Verses that were not words of Allah could have been added in and we have Evidence of this too.
.
This is why we find Verses in Qoraan that do not sound like they are words of Allah and a few of them have been even proven wrong by Science but who can tell this to uneducated Moslim Mollaas, who insist, "Every word of Qoraan has to be followed till Eternity", without realizing all this?
.
The Story does not end here. There are tens of thousands of 'AhaaDees' also and a lot of them are questionable.