The original language text WERE authoritative and any copies that are exact duplicates of the originals are still authoritative. The word of God isn't bound by words, there are many different words that can convey whatever was conveyed in the originals. However, some words can give even more revelation than the original words.
Almost everything written in the new testament was originally written in the old testament, but it was written vaguely and not direct and it was VERY HARD to see. The new testament came along and gave us the same story and message as the old testament, but in a direct way, a way that we could clearly see. The new Testament gave MORE REVELATION than the old testament.