1.) probably human, low on style but a solid twist (CORRECT) 2.) interesting imagery but some continuity issues, maybe AI (INCORRECT) 3.) more a scene than a story, highly confident is AI given style (CORRECT) 4.) style could go either way, maybe human given some successful characterization (INCORRECT) 5.) I like the style but it's probably AI, the metaphors are too dense and very minor continuity errors (CORRECT) 6.) some genuinely funny stuff and good world building, almost certainly human (CORRECT) 7.) probably AI prompted to go for humor, some minor continuity issues (CORRECT) 8.) nicely subverted expectations, probably human (CORRECT)
My personal ranking for scores (again blind to author) was:
6 (human); 8 (human); 4 (AI); 1 (human) and 5 (AI) -- tied; 2 (human); 3 and 7 (AI) -- tied
So for me the two best stories were human and the two worst were AI. That said, I read a lot of flash fiction, and none of these stories really approached good flash imo. I've also done some of my own experiments, and AI can do much better than what is posted above for flash if given more sophisticated prompting.