Everywhere you've listed your game's genre, you've called it an RPG. in your GDD, you even claim the game should appeal to strategy game enthusiasts. Despite that, there is no strategy involved when playing minutefighter, and little involved in creating builds. This is, essentially, an incremental game in disguise; Gameplay is simplified to expand the possibilities for progression, and the loop revolves around completing quests to get money to complete more quests.
Based on your GDD, i dont think this is where you expected your game to end up. That being said, i wish you'd leaned more into your game's real nature. If you continue this project, you should *strongly* consider a genre pivot. The card-clicking became a boring chore after a few runs - your game is practically *begging* for automation upgrades - some way for me to save on clicking certain abilities.
If i had to redesign this game, i would remove the 4-ability limit. All unlocked abilities are equipped all the time. I would start the player with only the sword, and i would add "Automation" upgrades that auto-cast older abilities. The core gameplay loop can remain unchanged: you can design the game so that the player is only actively using 4 abilities at once, but the game would demand variety and have a much better feeling of progression.