To wrap this thread up I just got news from Adobe Stock that they are accepting the image!
Don't bother with forums on these matters, just take it up with the stock. It is usually either something small that can be easily fixed or a random rejection that can be appealed. However, if they consider it something major and you disagree, then there is no point getting all lawyery on them, because it's their business, and it's a liability that you've got to respect. Just make another illo. Arguments lead to frustration which leads to loss of productivity.
A few examples of those small things: a friend of mine had an illo that among other things was displaying a laptop with a circle on it. The "copyright infringement" was that, as they said, "it looks like an apple" [Mac logo]. The conversation went, "but it's not an apple, it's a circle" - "to some people that could look like an apple". So she changed it to a square or something and the illo was accepted.
Another example - who would have thought that small details such as a fur-tree shaped air freshener in a drawn car or a smiley face as an icon on a smartphone could have a copyright protection? Apparently they do, so they were removed or replaced and the illos were accepted.
Happens to people all the time. Bottom line: ask the very people who rejected your illo why they rejected it, they will provide the best answer.