Rejected for quality reasons

Hello,

When using AI, still think about composition, use of colour and where you want the eye to focus, what part of the picture is important. Regardless of the medium, composition is very important.

Could someone point it out for me, what's the issue with those AI images in particular? 

By @MarikoArt

It's difficult when we do not see what the moderator saw.

Also, do rejections depend on the type of image (photo/illustration) or category (e.g. people or technology) - meaning, e.g. it doesn't qualify as a photo-people yet as illustration-technology it would? Or keywords - e.g. a man vs a sculpture? 

By @MarikoArt

Photos need to be photolike, your images are illustrations. Keywords will earn you a reminder or a refusal, if they are not relevant to the asset. However, a cat keyworded as dog probably passes.

And does "too many similar images already avaliable" (on Adobe Stock in general) get rejected as "quality issues", or is the stated reason different then? 

By @MarikoArt

There is a specific refusal for that: “Similar Image(s) Already Submitted”. You can get that refusal as well for pictures that are abundantly in the database, like red roses.

Is that the size and quality of the images as submitted?

Robot people have become something of an AI trope. I suppose they might still be accepted, but they have to be especially life-like and the robotic parts extremely well rendered. In 'portrait tech XCO,' for example, there are rendering errors throughout.

All 3  images are mostly blurry with very little in focus. 

Reviews do, to some extent, depend on the type of asset. In an illustration, such as yours, the need for the human-like subject to appear realistic is suspended to a certain extent. 

Moderators can select only 1 reject reason per asset; thus it's possible that an image rejected for quality issues might also have IP issues or a "too many similars" issue. In other words, if you fix the quality issue and resubmit, it could still get rejected for another issue.