Metaphor, allegory, parable ,,, whatever you devise to try and work around it, you'll not find the fundamental truth behind it to be a lie. I have no need to accomodate. It'll all reconcile in due time.
As far as your continued harping on poop, it was inert, digested vegetable matter at the time, bacteria notwithstanding. I suppose it dried out or otherwise fell apart, was spread around by various, natural means since toiling to produce food was unknown. Spread by the wind, trod by animals, whatever, but it became food for plants, primarily, and the creatures that feed off of it as well. Much like leaves or uneaten fruit, that sort of thing. No reason for this to be all that different from today, in other words. A perfect little "biosphere" that actually worked, actually sustained itself, with death being unknown.
Why is this so important to you? I honestly can't envision your rejection of the Biblical account of Creation as having hinged on such a thing.