rejection for QUALITY ISSUES

The majority of rejections are for technical reasons. Some can be fixed in post-editing, some can't.   Everything begins with proper lighting, camera settings and lens focus.

If the majority of your submissions are rejected, perhaps you're submitting work that needs closer inspection and editing first.

Compare & contrast your work with current Stock inventory in the same keyword. 

1. Is yours as good or better than what Stock has?  If you were the customer, would you buy it?  What would you use it for commercially— posters, t-shirts, billboard or magazine ads, etc...

2. Is your subject unique or are you competing with 20 million or more similar subjects?

3. Does your image have highest quality focus, good depth-of-field, proper lighting, good color saturation and a neutral white balance?

4. Is yours free of imperfections and unsightly distractions & artifacts— noise, sensor spots, lens flares, halos, etc..?

5. Does yours have good aesthetic & visual appeal?

These are important questions to ask BEFORE you submit.

Adobe has more strict quality guidelines than the other ones you mentioned.

Smartphone photos do not do so well with Adobe -the quality isn't so good when enlarged.

There are focus issues and composition needs work.

Have a read of this. It's a brief guide on quality:
https://helpx.adobe.com/stock/contributor/help/reasons-for-content-rejection.html

User guide:
https://helpx.adobe.com/stock/contributor/user-guide.html
Exposure:
https://www.adobe.com/creativecloud/photography/discover/exposure-in-photography.html
Composition:
https://www.adobe.com/creativecloud/photography/discover/photo-composition.html

20230617_080131-EDIT.jpg - focus is too soft

20230528_152657.jpg - you've missed the focus on his eyes, and the large blurry objects in the foreground are distracting 

20230529_163549.jpg - not well composed, and DOF is much too,shallow. Almost nothing is in focus.

The images with the boy are really good. Is it the same phone/camera as the other (bad) ones ..?

Focus is a problem in most photos. They need to be sharper. The photo with the child needs a property relase for the shirt and shoes and a model release for the child.

As quality requirements and checking are not on all sites the same, you need to live with the fact that Adobe stock is apparently the most stringent. Posting numerous pictures for volunteers to check is abusing of their time. Normally, we recommend not to post more than 3 assets.

Your first:

Artefacts, chromatic aberration. A correctly rejected picture. And it should also have been rejected on the other platforms.

Second: there should be some structure visible in the shadowy areas.

Artefacts in the sky:

third: artefacts, no details, no good focus. Furthermore, I believe that the chessboard you used is not of high quality.