I only learned about aphantasia a few years back and, like you, so many things in my life just clicked when I realised I was an outlier.
I could never relate with people when we'd read a book that had become a movie and they're like, "but they're not at all how I imagined them" and all I could think was "but the person in the movie has the exact characteristics described in the book!"
When people would ask me to imagine something then ask questions about it, I'd basically just be deciding details on the fly and then retaining them in a list. For example, if you said, "think of a car," inside my mind is just "a car" on repeat. Then if you asked me what colour it was, I might decide "red" and my mind is now, "a red car", etc.
I remember the massive hubbub about the Mortal Engines movie specifically.
The only thing I remembered about the main character was that she had a scar on her face.
Fans were nitpicking every single strand of hair and I was like "You guys remember that, do you make notes when reading or what?". Apparently people visualize books so hard that they "see" the characters and remember them.
I could never relate with people when we'd read a book that had become a movie and they're like, "but they're not at all how I imagined them" and all I could think was "but the person in the movie has the exact characteristics described in the book!"
When people would ask me to imagine something then ask questions about it, I'd basically just be deciding details on the fly and then retaining them in a list. For example, if you said, "think of a car," inside my mind is just "a car" on repeat. Then if you asked me what colour it was, I might decide "red" and my mind is now, "a red car", etc.