It is not a very responsible exegetical approach to read a text and say “Well, if it matches what science says or what is historically likely, take it literally, if not, it’s a metaphor.” That is an unfortunate caricature presented by people who feel threatened by having their interpretations challenged.
No responsible Bible scholar is actually approaching the Genesis or other OT narratives that way. If I come to the conclusion that Jonah is not an objective historical account but is a kind of theological drama intended to teach about salvation, judgment, grace, and the character of God, it is because there is evidence in the text itself that points to interpreting it that way. It’s not because I refuse to believe a man could live in a fish for three days. If I think maybe the story of Noah has been mythologized or appropriated for a purpose other than strictly recounting history, I need to argue that from the text and the cultural context as well as from the rocks and the artifacts. If I see the seven days of Genesis as a literary structure that frames God’s ordering of creation and purposes for it and a polemic against the deities and religious beliefs of the ancient near east, instead of a blow by blow account of the literal order and events of physical creation, it’s because there are abundant textual reasons to interpret it that way. It’s not because I refuse to believe God could speak the universe into existence in six days.
There are lots of reasons to approach the Gospel accounts with different interpretive lenses than the first eleven chapters of Genesis, or Revelation, or Paul’s letters, or the Psalms. Plenty of brilliant people have spent their lives studying these texts, the cultures that produced them and the cultures they were in contact with, and they offer tons of insight into how the stories were understood and used in their original context. We shouldn’t think that we should be able to sit down with our translated Bible and the Holy Spirit and understand everything there is to know. We can understand enough to know the truth about the important things, but some of the details are hard. Some interpretations are highly debatable and we just don’t know for sure. There is work enough for a lifetime putting into practice the things that come through loud and clear though, so at some point you have to decide not to sweat the small stuff.
I think these two blog posts highlight forum conversations that touch on some of the issues you bring up, if you are interested.