If I can ask people with aphantasia...
How do you remember things? When I remember the past I see the ephemeral image of what I was seeing then. And there is a thin line between memory and fantasy - I can play with my memories and let them play out some other way than they happened.
How do you read the books without imagining what is happening? How else do you convert letters into meaning?
What happens in your head when someone says "a car"? I see a vague image of a car - right now it's a red sports car but I have no idea why and I am not sure about the brand and it's kind of general car without specific features but if you ask me, I can immediately imagine the details of wheels or whatever - and some other day it might be a black BMW.
How do you imagine your future? I can see myself sitting in a place (inspired by a photo I saw and liked) with big wooden bookcase in a bright room lit by setting sun - and that image makes me feel something and motivates me to work towards it.
And fear is also visual - like when I see myself getting hit by a car when I am on a bike, with the blood and dirt in wounds... I could continue like this for long time - it feels like seeing things inside my head is so "normal" that I cannot imagine functioning without it. It is fascinating though.