It is said by intelligence sources that the ancient scriptures were written by Man. dont think this will be accepted by many,but it may be true.
The self realization point of view when reading them is that they are written by"yourself".
In the same way as the Budha says that he is the god himself, it could be said in the religions that " I am Christ, I am god, I am moses etc. Also "I am antichrist , I am the devil,,etc. The budha would also say the he wrote the scriptures, So would a Christ or a Rhadakrisna.
It is self realization.