Hate to be the bearer of bad news but if you can’t relate to mental images existing in a visual sense you probably have some degree of aphantasia.

Some research indicates that it may be a spectrum from complete lack of imagery to full five-sense detail, which might be why it’s hard to relate to either extreme. At any rate most people fall in the category of seeing an image, to the point that hyperphantasia is even more common than aphantasia.

I have it*, but not as severe as others. Imagining an apple starts as a very abstract concept, I can’t visualize it without concentrated effort. Other people might be able go on to describe the stem, the leaves, the shade of red, the glossy wax exterior, etc… I can’t automatically build to any of that, even if I subconsciously default to a red apple the “image” may just as well be green.

*edit: checked the vviq test and discovered the label is hypophantasic