I think the idea is really great but I would say one reason is because of too much noise in the image. There is also colour noise - as around the shadow of the person there are lots of specks of colour - it is not completely black. Also if uploading to Adobe do not include any watermark but you may not have done that on the original. Hope that helps a bit but I am only learning myself and I will soon be posting and asking for feedback too
Before submitting photos, ask yourself these questions.
Please re-read content requirements from the User Guide.
Also refer to these help articles:
Better luck with your next submission.