Just because the autographs (original documents) of Scripture are unavailable to us today, the ascription of inerrancy to these documents still stands. Restricting inerrancy to the autographs enables us to consistently confess the truthfulness of God. Only with an inerrant autograph can we avoid attributing error to the God of truth because he, in the pages of Scripture, takes responsibility for the very words of the biblical authors.
To assert that God could breath forth a word that contained mistakes is to say, in effect, that God himself can make mistakes!