I recently sent 7 photos to myself using iMessage from my iPhone so that I could have access to them on my Mac (it's faster than AirDrop for me). They appeared in Messages on my Mac, and I was able to double-click on them and look at them individually.
However, when I tried to copy and paste any one of the 7 photos, either from the text or from their own (Quick Look) photo window, pasting would just paste all 7 photos, instead of the one I’d copied.
I tried copying using shortcuts and menus. I tried pasting into Messages. And I tried simply pasting into a blank file. All those actions resulted in my only being able to copy and paste the 7 photos instead of the desired 1.
I was able to drag-and-drop with a single photo, though this seems insufficient given how unpolished this feature seems to work within Messages and elsewhere.
If copying and pasting individual photos is possible, any info would be much appreciated!