Very cool prototype. I relate to the theme on a personal level - I am statistically prone to developing dementia, as it runs in the family. I have always strived to create a game that encaptures the loss of memory, and while this game is not quite that, it does deliver a similar message.
Aside from that, the gameplay was alright. I agree with another comment about feeling like I needed more checkpoints, but that is more of a shoving-it-under-the-bed solution to the actual problem. It's surprisingly likely how often I'd just fall off of things. Whether it is due to unclear hitboxes, the controls, or whatever, it would happen. And this where the lack of checkpoints would frustrate me; if you're not activating new words as you go, the game is pretty stale. So additional checkpoints could alleviate that, or finding a way to prevent unnecessary deaths.
But overall, I enjoyed the message and the boss fight was funny. Perhaps you could check out my game and give me equally honest feedback - because everyone can improve!