I have no preconceived ideas when I read anything.
When I read a series of books supposedly based on the prior books and there is no connection in reality, I then know it's not a series of related stories.
Thanks for proving my point. If you are referring to the Koran (which I assume you read in the original Arabic) your faith informs you that the 'prior books' are accurate so the differences found in the Koran mean it must be incorrect. If you didn't let your preconceived ideas cloud your understanding you might accept the Korans assertion that the 'prior books' are not accurate accounts so God really did send his messenger with an update.
Be honest...
Have you ever read the Koran?
I read the first 10 suras.
Tried numerous time but could never get through it. On the other hand, over a billion people probably have. I'm not sure I'm qualified to critique the (possible) word of God. You claim you must read the Bible in its original Hebrew to appreciate it, the same may be true of the Arabic of the Koran. Allah may take us to task when we die for not reading his book. Could happen.
At any rate, I think if we believed the Koran was truly the word of God we'd get through it. Gotta have faith.