Unfortunately I can't say I've got much knowledge about Christian scripture. Regarding its preservation most of what I know is derived from the debate of well-known Christian scripture and textual scholar Dr. Bart Ehrman.
"Bart Ehrman & Daniel Wallace Debate Original NT Lost"
https://www.youtube.com/watch?v=wyABBZe5o68According to Bart Ehrman:
No complete manuscripts of the Bible from the first, second and third centuries exist.
From early second century only 1 manuscript of the Bible, which has a few verses written on it, has survived.
5,500 manuscripts of the Bible survive, of which 94 % are from the 9th century.
In short what Daniel Wallace said (similar to what you are affirming here) was that due to the vast number of manuscripts that are present and the hundreds of thousands of variances (most are insignificant) in them is a proof that we can reach the original New Testament text.
However, Bart Ehrman is skeptical of this concept or even convinced against it. He seems to believe that the probability of the loss of the original New Testament text is very high by giving an example that it would have taken only a single inaccurate or malicious copier of the New Testament in the first century to corrupt all the manuscripts that are presently available.
I completely agree that hundreds of thousands of the differences in the manuscripts are mostly spelling mistakes and such, as Bart Ehrman admits but according to him some of these differences are significant enough to question core Christian concepts.
In another debate that I was once listening to, the example of 1 John 5:7-8 was given. According to my limited knowledge, this was the verse which most explicitly confirmed trinity in the King James version of the Bible; but, according to new information obtained, in the 1980s its words had to be changed and the present version doesn't appear to be affirming trinity.
It is possible that the present version of the Bible might be the accurate one, I say this because of the "Christian Vs. Muslim" debates that I've listened to, both debaters use the Bible as a source of information. Christians interpret a particular verse a certain way, Muslims another, which is something Muslims apparently have common with nontrinitarian sects of Christianity.
However, as Bart Ehrman argues there is no way of knowing that. There is a reason that textual criticism is still going on, because there is still some work left. Maybe in the future we will be able to obtain the original words of the Bible and even prove that but presently (according to Bart Ehrman) we cannot be sure.
Regards.
