There is mythical gods and then there is fictional characters in comic books and movies. Next, the "Author", I assume you mean God, wrote symbolic expressions you say to relay inner meanings. But, then you say only God can reveal those hidden meanings. And when is that? Now? With Baha'u'llah? That the true meanings were hidden for hundreds and even thousands of years?
God does not reveal them, untill the time is right.
You can see same concept explained in Buddhism Scriptures:
It is recordd In The Sutra of Mañjuśrī’s Questions
That Mañjuśri asked Buddha that, if the Buddha is omniscient, why does he not realize ahead of time
Budhha ....etc etc.
Buddha answered:
Mañjuśrī, I am like the doctor. I understand that sentient beings mayh ave predominantly great desire, great anger, or great stupidity, and that
they may have a long or short life span and evil or good karma.
Although I have prior understanding of these things I do not speak of them when
the time is not right.
....
If any sentient being is able to listen to the Dharma, I will preach it for them
If they cannot stand to listen, I will not do so.
....
Compare these words, with what Jesus said to His disciples "
I still have many things to say, but you cannot bear it now!"
Thus, Christ and many Prophets did not speak explicitly sometimes, if people of Their time were not ready to know. Instead, They spoke using parables, figures, Metaphors and riddles. In this manner they did not explicitly say things, but left it for a future Manifestation to reveal it, when the time was right and people were ready to here!