No verse says all the bible is a parable. We should only believe something in the bible if it says so . This isn't the trinity where its something as hard as God could try we wouldn't fully grasp .
10¶And the disciples came, and said unto him, Why speakest thou unto THEM in parables?
11¶He answered and said unto THEM , Because it is given unto YOU to know the mysteries of the kingdom of heaven, but to THEM it is not given.
12For whosoever hath, to him shall be given, and he shall have more abundance: but whosoever hath not, from him shall be taken away even that he hath.
Whos the them ? Jesus is not speaking parables from 12 years old to revelation lol . Nor is the bible a complete parable. No he speaks in Parables at a specific time ,for a specific reason to specific people .
Simple. I didn't need to speculate , assume or give you my ' opinion ' . Its what it actually says .