That's a good question. However, what is written in the Holy Scriptures is, in the first place, the letter.The Bible is God's word. As 2 Timothy 3:16 says, it is inspired, or breathed out, by Him. You say that unless we have a divine revelation from God of Who the Lord Jesus Christ is, our understanding cannot be said to come from God. So do you believe that the Bible is a book written by men and not the word of God?
Although it is truly the Word of God, Scripture says, "the letter kills, but the Spirit gives life" (2 Corinthians 3:6).
Therefore, you cannot simply conclude that the literal meaning of the written words is, in itself, the fullness of the truth.
It is God's revelation of what is written that makes His truth known.
The Spirit reveals the deeper, spiritual meaning of God's Word, and it is this revelation that gives life.
Without God's revelation, a person may understand the words intellectually yet still fail to grasp the spiritual truth God intends to communicate.
Have you still not understood what is written in John 2:19–21?
When the Lord said, "Destroy this temple," the word temple, although it was the Lord's own word, was not yet the truth in its intended meaning.
JOHN 2:19-20
19 Jesus answered and said unto them, Destroy this temple, and in three days I will raise it up.
20 Then said the Jews, Forty and six years was this temple in building, and wilt thou rear it up in three days?
It was the Lord's revelation that the "temple" referred to His body that revealed the truth. The spiritual meaning disclosed by the Lord is the truth, not merely the literal word itself.
JOHN 2:21
21 But he spake of the temple of his body.