My main competitor is there in the answer box, as they always are, but my image is next to their content.
Barry mentioned in the seroundtable article I'd cited above that this kind of thing might happen... and he predicted that some SEOs wouldn't be happy about it, but he also noted that this is how it has worked for years in
"Top Stories or News box content", and everybody's survived. It could even be argued that it's giving two pages links up top rather than just one.
Keep in mind... Google has separate criteria for images in serps... Over the years, we've had several threads here about Google's image choices in serps, in particular for image thumbnails in News content, and also for the thumbnails in recipe serps. Those were mature areas. This is brand new.
The news discussion in particular discussed a broad range of factors that might affect image inclusion, with regard to their labeling and positioning in relation to text, image size, aspect ratios, image file formats, etc, and how well they worked with Google's guidelines...
at that time, years back....
Google News help - how to get thumbnails in news feed Jan 2010 https://www.webmasterworld.com/google/4067802.htm [webmasterworld.com]
Some concerns still apply. Some don't. I added some thoughts about image composition, and how these images would work when resized as thumbnails, which I think might still ultimately be applicable.
There was also a question about whether performance in Google Image Search might be a factor. Again, this was about desktop pages, pre-mobile.
Today, the "featured snippets" (or "answer cards", as I too have tended to call them) are being extracted primarily to feed quick answers to short attention spans on small mobile screens. Among the requirements is that they work responsively, that they read quickly, and that they satisfy user intent.
I'm not finding any image submission guidelines now... but it would be helpful to know if there are any, should anybody see any.
Example images I've found recently are all set to work responsively on their source pages. Some images used were very popular in Google Image Search, but some weren't.
It's interesting that for the "how to" searches I tried, some images were purely diagramatic... answering "how to" do whatever... but one, having nothing to do with explaining the mechanics of the question, was a completely cutesy shot of a toddler... because The Answer was about teaching this to kids.
As I've noted, I'm seeing some images change over a short time for the same search, and I assume that Google is still sorting out what it is that works the best for various types of searches.
...search... to see if a newly purchased image on my site...
browndog, I think you're overly optimistic about how fast new images are likely to be ranked, and you're probably watching these serps way too closely. Google is going to go through a thousand changes on these. Try to look at these with a dispassionate eye, and to figure out what user needs Google's algos might be trying to satisfy with various choices of images.
IMO, choices are being made by the same kind of deep learning algo that powers RankBrain... and it's really just taking its first baby steps.