Because the Bible has changed so much over the years it is hard to see how it can be inerrant. Take for instance Mark. The last true verse in Mark is 16:8. The rest was added later by someone who felt that the ending kind of left people hanging. Also, if you read the resurrection accounts of Matthew, Mark and Luke you will find they don't match. They differ wildly in fact. Therefore, the Bible is not inerrant. Only one can be correct. These are just a couple of examples out of multitudes.
You've been reading Bart Ehrmann again, you naughty boy. Poor Bart doesn't understand proper textual criticism when it comes to the Bible. All the discrepancies can be harmonized. You need to read F.F. Bruce, and not claptrappers like Bart Ehrmann. As far as credentials are concerned, F.F. Bruce's credentials trump Bart Ehrman's by a long way.
There are indeed human errors that have been made in copying the various manuscripts down through the years. A vast majority of those errors involve spelling, a word left out, transpositions, etc. As for the supposed "major" errors, which are few and far between, those "discrepancies" can be resolved with proper textual criticism.
I believe we don't have the original manuscripts because God wants us to worship the One that is written about and not the writing itself.
I would be happy to forward to anyone a good article published by Ron Rhodes concerning the accuracy of the Bible. This article makes it clear that we have more than enough manuscripts that date back to within a generation of the original manuscript, and writings from the early church that quote the scriptures to assure us of an accurate Bible that indeed has not changed one iota since it was written.
So much for human reasoning. Now let's see how God has handled these supposed discrepancies.
2Timothy 3:16 All Scripture
is given by inspiration of God, and
is profitable for doctrine, for reproof, for correction, for instruction in righteousness, 17 that the man of God may be complete, thoroughly equipped for every good work.
Hebrews 4:12 For the word of God
is living and powerful, and sharper than any two-edged sword, piercing even to the division of soul and spirit, and of joints and marrow, and is a discerner of the thoughts and intents of the heart. 13 And there is no creature hidden from His sight, but all things
are naked and open to the eyes of Him to whom we
must give account.
John 14:16-17 16 And I will pray the Father, and He will give you another Helper, that He may abide with you forever 17 the Spirit of truth, whom the world cannot receive, because it neither sees Him nor knows Him; but you know Him, for He dwells with you and will be in you.
Numbers 6:24-26