I Need Help. I was rejected and have no idea why

Here was what I received.
“Thank you for your submission. We have completed our review of “Light Green Pie Slice PNG Set” and unfortunately we found it isn’t at the quality standard required to move forward, and you won’t be able to re-submit this item again.”

I submitted it under Graphics but maybe I picked the wrong category. It’s just a PNG that doesn’t need to be layered (at least that’s what I am thinking), so I am confused. My piece is attached and any helping feedback is welcome.

Thank you,

Hi @Staffatico

I think that your design is too basic bad colors.

I invite you my friend @n2n44 he know more that I and he is graphic designer and experience 16+ years for give you best your advice, regards.