I was relatively competent at art because our teacher emphasized having a model to look at while we were drawing. I can also draw faces because she taught us a method on how to do so: place the eyes halfway down the face, place the nose halfway between the eyes and the mouth, etc. Essentially, I can draw faces by remembering a list of instructions and how I moved my hands–the process. The problem with this is that I can only draw generic faces if I don’t have a model because I don’t understand the details beyond the main concept. I can’t draw anything I can’t see unless I’ve drawn it before and remember how, and even then, it wouldn’t be a great reproduction.
I’m not an artist proper, so I don’t really do much outside my art classes because I’m not motivated, but the way I create original pieces is by planning out objects and where I want them to go in the piece, then either creating a model by arranging those objects in real life or by finding pictures of each and learning how to draw them individually before drawing them all together. I prefer graphic design over drawing because I can take existing images and splice them together in Photoshop to make something new, and it’s still technically art! I never know how it’s going to turn out until I’m looking at the finished product, though . . .
Since I’m so process and concept oriented, I sometimes use my art training to help me break down what I’m seeing into something I’ll understand and remember. Thus, I remember, say, a beautiful sunset not because I can visualize it, but because I can remember planning out how I would draw it or paint it, assuming I have the skill to pull it off. I don’t know if anyone else does that, but sometimes it helps me remember visual details that I would have no access to otherwise.
It sounds like your art class was not taught very well, at least not for people like us. I’m sorry that put you off art. It can be very fun, even if you’re like me and you’re only average. It’s possible you might be better at it if you can get someone to teach you according to a different method, but it’s okay if not.