OK...you proved by the Hadith that the Quran was preserved by the Quraa (the poeple who were able to read and who memorized the Quran.)
You are asking about 19 years after the death of Prophet Muhammad....what about 325 years till the Council of Nicea? what books were authorised for the christians......how many books were there and how many remained.....you know of course the amount of differences between the different bibles present nowadays....and how each group of christians accuse the other of being wrong......
You said that muslims don't have the original copy of Quran....look at the pictures please, they are now in the museum in Turkey.
http://www.mrooj.com/mashafs2.jpg
http://www.mrooj.com/mashafs3.jpg