While the books of the Bible contain references to scripture that is currently unavailable, there are also many different versions of the Bible which contain different books. It is a false notion that the Bible has been and is a fixed set of scripture. Various editors have removed and added books to their version of the Bible based on their beliefs. Further the text of the Bible has been altered by copyists over the centuries.
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Typical disparagment of the Bible.
As early as the 4th century we have the full canon listed IN THE CURRENT ORDER. The ‘varients’ of the Bible are miniscule mostly involving word order or spelling variations that are easily determinable. There are less than 250 actual variants and NONE of those affect matters of faith or doctrine.
I would recommend, as introductory works, From God To Us:How We Got Our Bible - Norman Geisler (Author), William Nix (Author) and also The Canon of Scripture by F.F. Bruce.
I would be impressed if it was even the 1st century, but alas......
As for variants, there are many important ones, such as Pericope Adulterae. However, the most important point is that the original manuscripts are not known. In spite of this, many christians, including those of my own faith, believe the Bible to be divinely inspired and part of our canon scripture.