Please explain why images were rejected for quality?

Not sure what the commercial value is for dandelions these days.  Adobe Stock has 100+ pages of them.

https://stock.adobe.com/search?k=dandelions

The pink rain boots might do OK if you clean up the quality to be as good or better than what Stock has.  Compare yours with current inventory.

https://stock.adobe.com/search?k=pink%20rain%20boots

Good luck.

8400: You have artefacts. The dandelion would probably have to be rather sharp?

In addition, you should lower the exposure, the skin is to light.

8402: out of focus and the same problem with the dandelion. Same skin problem.

8300: White balance issue (too warm), not as sharp as it should be.