It's not a metaphor, it's a poetic description (or an allegory, if you like) of something that really happened. It may be Adam and Eve and the snake did not exist within a literal interpretation of the first bit of Genesis. There are lots of arguments for this: for example, that part of Genesis is written as a song - it even has refrains and a poem-like structure, which is NEVER seen anywhere else in the Bible as the structure for a historical account.
It's also severely lacking in detail for a historical witness account, and even for the knowledge at the time it was written, it doesn't make much scientific sense (days happen before the sun is created, etc). And the observer is never identified throughout - everything happens in third person (or rather, the zeroth person), from a totally separate narration, in the form of a song. But ultimately, it doesn't really matter what you believe about the first part of Genesis: ALL Christians believe that Adam and Eve existed IN SOME FORM, whose story follows a direct pattern of how Genesis portrays it.
There WAS an Adam and an Eve, and they DID commit the first sin, that separated us from God in the first place. And you are correct: if there was no Adam (in whatever form he took - man, family, generation, whatever), Christianity's message doesn't make sense. Https://www.youtube.com/watch?v=wf94J3xG...
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.