This may be as hard for Muslims to understand as it is for Christians. No, you don't have the exact and perfect one.. There is no, "Original" like you are looking for.
Ashes to ashes, originals decay if they aren't destroyed first. Copies were made, memories were tested, commissions agreed, standards were accepted, books were compiled.
I've studied a lot of the similar structured Christian questions.
Here's what I've broken it down to.
God, Allah, wrote ten commandments... in stone and we don't even get to see them.
Everything comes to us through humans. Regardless their purest of intents they were all humans. Much of it was oral, much of it was scattered.
There are archeologists spending millions of somebody's money dusting off old stones and pretending they know what empire, what age they came from. Regardless what they find, there's controversy.
It's now said King Solomon's kingdom was not as large as described, but they cannot be sure what size his it was, they think there was another empire beside it, uh, none the less the Biblical story must have been embellished. What do you believe? What do you want to believe? Does it make a difference to you?
Much of the textual criticism of the Bible run along the same lines.
You can spend a lot of time trying to figure out whether the past is true or not or if it even made a difference but in the mean time, Allah waits for you in your Quran.
The world wants you to question everything. Let the fools question God's capability to keep His scriptures inspired. They will distract you from what really counts and that is, your time with your book and your God.