This sort of topic is relatively common. Aphantasia gives it a new twist, and I'm not sure at what level aphantasia matters (and I've chatted with people on r/chess and r/aphantasia about it) but for beginners (IMO) it doesn't matter at all.
Mostly it's about this:
https://www.chess.com/forum/view/for-beginners/the-most-important-concept-for-all-beginners
Mostly it's about this:
https://www.chess.com/forum/view/for-beginners/the-most-important-concept-for-all-beginners
Thank you for taking the time to respond.
I completely understand everything in that post you shared and it makes perfect sense. But to give an example from a recent game, I looked at where my Knight could go to stay safe after it was attacked. I thought that their Knight couldn't physically get to the square my Knight was going to but then discovered on their move that I can got it wrong. I saw the move, I just couldn't hold an image of my Knight and their Knight in my head and managed to get the squares muddled up.
Conversely, in a Daily game where I can use the analysis tool to physically move pieces, I generally only make blunders if I judged them (incorrectly) to be worth the risk. I just don't like how long Dailies can take.
I have no idea if this makes sense at all?
Sure, a common beginner mistake is moving pieces to squares where they can be captured for free. There are a lot of pieces and a lot of different ways they can move, so sometimes mistakes happen.
Knowing how a knight moves has nothing to do with mental images though... I mean, if that were an issue for you, then half the time you'd be trying to make illegal moves right? 
I remember one daily-style game (multiple days to move) I was playing against a friend. I had already been playing chess for a few years, and I was pretty experienced.
Well, one position I calculated for a while, double checked everything, and played my move... the problem was I missed that my move allowed him to checkmate me in 1 move.
Mistakes happen, but the more you play, the more patterns you learn, and the better your calculation habits, the less common the mistakes are.
Of course, it's possible for someone to not be good - most people start in this position. What I mean is, is it possible for someone to never progress beyond that point?
I haven't been playing long. I'm mid-30s, learnt how the pieces move as a child and only discovered that other people that aren't grandmasters actually play about a month ago. I also have aphantasia (I have no visual memory or thought processes). All this is to say that I expect that any progress I make to be slow at best.
That being said, I would have hoped for some progress by now instead of feeling like I'm in a place of stagnation with the 550 rating I had at the end of my first day playing seeming to be unobtainable now. I have tried learning some simple openings, tactics (I'm not too bad at puzzles with a rating over twice as high as my rapid) and endgame drills. I just can't put any of it into a game.
I feel like my basic understanding of how the game works is completely wrong and I just can't see simple moves unless I learn the muscle memory of the exact pattern which, considering the exponential number of moves possible in a game, feels like a bad way to learn.
I really enjoy the game but I'm now at a point where I don't want to invest money into courses and books if a) they're the wrong ones for me (anything with visualisation exercises is a waste of time) , b) is the wrong path to go down to improve or c) I'm wasting my time trying to as I've already hit or am close to my ceiling.
Does anyone have any thoughts or suggestions?