Okay, so I took a look and overall, I don't think this professor is targeting you or grading you unfairly. I did take a look at the original poem, as well as your arguments, and I do agree that a queer lens could certainly be applied to the poem. However, the way you're talking about the story makes it sound like an explicitly homosexual text, which it isn't. I think a lot of that is a product of the assignment being a short response that doesn't really give you the scope for what is ultimately a pretty complex argument about the text that needs a lot more breathing space, or maybe your research on other scholarship about the poem giving you the impression that a queer theory reading of the poem is a settled fact rather than one interpretation. However, it is also true that there is no explicit homosexuality in the text. I also think he's right in that it's difficult to follow your line of argument about what was asked in the prompt re. the view of human nature in the poem. You're pointing at some different ideas about Adam and Eve, the Old vs. New Testament, a third reconciliation beyond the two. It's ultimately too overambitious for what the assignment is.

I also look at the professor's feedback, and it's critical while being encouraging. He's appreciative that you tried something here, although it didn't quite work and acknowledges some of your writing strengths. If I got this from you, I would think that you were a strong, but still developing academic writer with a lot of interesting ideas that needs some work on the underlying structure and fundamentals of argument and interpretation that will support the more complex analysis you're trying to do (and a better sense of what's possible within the scope of the assignment).