knocked back for exposure, histogram seems ok

There is too much shadow in the hand and truck. You need to bring more detail in this area.

However, maybe you could post an actual image, rather than a screenshot, as a screenshot is not so good for analysis.

But the main thing here is having the hand and truck in shadow, It needs to show more detail. Basically, the hand and truck are underexposed. I assume this the most important part of the image.

Hi Ice_blue,

Welcome to Adobe community of photographers. For the purpose of stock photo, images, back lighting should be for the purpose of separating your subject from the background or to blow out an unwanted background, rendering it white, but not to cast a shadow on the subject.. Your main subject should be well lit, but not over exposed. 

Look at it this way. A customer likes the hand with the toy, but do not want the current background; if properly exposed will still licence your image but crop out the subject and place it on the background of his choice. The shadowy hand you present would not work so well in that case. 

This is what you need to do. reduce the highlights and possibly white also, and increase the shadows, and black so that the hand becomes better lit, and the highlights as you have it becomes softer. In the process you might need to touch up exposure a little.

In addition, you need to pay attention to white balance. Your photo seems to have a red cast.

Different stock photo platforms have different criteria by which they accept images. Even on those platform that accept shadowy images like this one, my experience is that the better lit images are more likely to sell.

After you have made the adjustments, you may resubmit for another review.

Best wishes

JG