“Dumb” of course means it does not speak for itself and that is true. For if the Bible truly spoke for itself there would be no disagreement as to what it should contain (canon) or what it means (interpretation).
“Difficult” - the Bible clearly is difficult in parts.
So?
The Bible can be difficult to our fallen minds. Jesus told his disciples that the Holy Spirit would help them with understanding.
But of course we all know the Scriptures cannot be that difficult if Fishermen and goat herders got it.