New to this...wondering why this was rejected.

Hi,

welcome to the world of Stock photography. In addition to what has already been written, I would like to add that with this type of photography you should always pay attention to the fact that this type of image is very often used to advertise and sell products or services. Not every photo that looks beautiful personally is also suitable for the advertising industry and sells well.

Before you submit, please review the submission guidelines carefully and compare your work with other Stock inventory. To be accepted, your work should be as good or better than what's already represented in your keyword category.

https://helpx.adobe.com/stock/contributor/help/reasons-for-content-rejection.html
https://helpx.adobe.com/stock/contributor/help/quality-and-technical-issues.html  https://helpx.adobe.com/stock/contributor/help/photography-illustrations.html
https://helpx.adobe.com/stock/how-to/tips-stock-image-acceptance.html

Hope that helps.

For a bad photographer, your picture is pretty good.

It's lacking contrast and the shadows could be lifted a bit, but all in all, it's not bad. I suppose, however, that you needed to lift the exposure of the stones in the foreground quite a lot. You have made a small, noticeable editing error on the left side:

The iPhone is not the ideal camera for such shoots, as the light situation is difficult. You can try to edit again (start with the original), it may be that you can overcome the difficulties and resubmit. If you don't get the picture quality as required, use it on social media, it will get plenty of likes.

Shooting at the sun is never recommended.  Also it's a good way to burn out your camera sensor.  If you're new to photography, keep the sun directly overhead or slightly behind your shoulder while you're learning.  You'll get better results and prolong the life of your camera.

As you gain more photography experience, you will learn to use polarizing lens filters, shades and stacked exposures at different camera settings to achieve more professional results with sunset shots.

If you zoom in on the foreground rocks you see soft focus and noise. The lens flare might be an issue too.