I suspect the pastor was doing his own spin on Joel Osteen's "...I am what it says I am..."
one huge meta-narrative with various layers of narrative going on underneath that.
Start your logic simpler than that. Even being the Word of God, it is safe for a believer to admit that in the Bible, human beings wrote about their experiences, their interactions with God and supernatural beings, their insights, and their hopes.
Generations of believers cherished these writings, and used them to draw closer to God. To understand His heart for people and to follow His guidance. The book was not one big book until hundreds of years AD.
Picture how Christians write books today. I don't want to minimize the Bible, but there are similarities. They tell about their experiences, give advice, talk about miracles God has done for them, analyze previous writings... narrative or not, God still speaks through them.
Many Christians are offended when hearing talk like this, how humans did the writing, but I don't see it as any less the Word of God -- because He is the God who chooses to dwell within us. He sent His Holy Spirit to guide and comfort, empower and enlighten. So being human and a writer does not make our written expressions completely human, or completely divine.
As for all parts being literally true, just start with it being a respectable historical document. The creation story has similarities to stories of other early civilizations -- same planet. Archaeology has proven some of the stories true, and many of the miracles naturally credible.
Be careful if someone is pressuring you to believe something that you have not found the logic for. That is how cults get a foothold. Ask God to help provide the logical connections, and He will lead you to readings that help make sense of things.
God asks that we follow and trust, not that we brainwash ourselves and disrespect the brains God gave us. Once we give up our right to make decisions, we also lose our grounding to discern beneficial from detrimental.