I love the idea! It's a pretty original take on the typical clicker-type games, I really like it! I think it has a lot of potential to be upgraded to become even better, so I do hope you'll keep working on it like intended!
Here are a couple ideas for the upgraded version that the prototype inspired me :
-Upgrading a category unlocks new words in that category in addition to more money per words
-The decor elements could appear more progressively, I'd suggest having them appear one by one as you type the corresponding words (ex: every time you type "tree", one more tree appears until they're all shown, or they get more covered in leaves while you type "leaves")
-This could also improve the upgrades, as you could unlock new upgrades, or new word packs depending on how much you've progressed in one, or require having completed X words of one to access to the next
-A dictionary of words you've unlocked could be a fun addition as well
-A visual indicator of how much typing the word has earned you