It sounds like what you are trying to do is what I do for music folders. I like to show the album cover instead of the standard folder icon and when you double click on the cover, you see the files as per normal.
Find a picture you like and save it as "folder.jpg".
Open https://converticon.com/ in your browser, select the "folder.jpg" and convert it to an icon file and name it "icon.ico". I tend to select all size options, but that is up to you.
Create a file called "desktop.ini" and into it put:
Put the three files (folder.jpg, icon.ico, desktop.ini) into the folder of the image you want to change.
Open up File Explorer and navigate to
Ctrl-a and delete everything there. Not everything deletes, but what you can delete seems to be enough. Before deleting, make sure all the folders that you are wanting to update are either closed or in Display/List mode.
Next, update the read attributes of the files. Open Command (cmd) and type
attrib +r C:\<path>\* /s /d
The path of the root of your working folder is fine. In my case I just find the folder that contains the artists and let the album directories work themselves out. This command will give read only attributes to every single thing.
Finally in the command window again, type
attrib -r C:\<path>\* /s
to remove back readonly from all files, excluding the folders.
You should now see the folder as the image you desire, all other files, folders etc will be as they were before.