The entire premise of the bible and the entire key to salvation is believing jesus is the son of man and that he died for your sins. Without that your missing the entire point of the book. He was a martyr for our sins. The only perfect being to ever exist took on the burden of our sins by dying on the cross.
The disciples were chosen by god to translate his words thru the bible divided in to books or sections. Example, book of matthew, mark, Luke, John etc. All NEW testament. He used very unperfect people to demonstrate his works. For example Paul the apostle killed and murdered christians before god used him as a vessel for christ.
Now to your last statement, in the late 1940's we discovered the Dead Sea Scrolls which has more or less added to what we believe the bible should of been in its entirety. Interesting stuff for sure. Stuff that wasnt in the widely accepted king james version
25 Fascinating Facts About the Dead Sea Scrolls @ Century One Bookstore