We are left with a mountain of physical evidence in the form of manuscripts. Yes, they are copies, but the copies can be compared to determine which is the most likely original wording. That's the science of textual criticism.
And there is no other way to do it.
Bible translators have been removing and adding verses since Bibles were first compiled.
We know the KJV has had verses added and removed just like modern translations.
We shouldn't panic at the thought. It's a wonder it has survived at all let alone with the few differences we find.
Rather we should marvel that this ancient work has survived 2000 years (much longer for the OT books) and had such a
massive impact on humanity. The most important collection of books mankind has ever known.