This game is going places. I have tried all "Inflationlike" games, my favorite being Resolute hero for his really good item drop system.
It would be really cool to add something similar, like before starting a battle there is a little "?" square letting you know that peon has an item drop you have still not collected, when you already collected it, it shows the item drop in the same box for next fights. This way it feels more transparent and there isnt a need to constantly be looking for guides for the good drops.
The exp system is genious and really like it, there is alwais a feeling of improve after every run thanks to it.
Being able to play on different character with different stats and items feels refreshing and the addition of the skill tree, despite being too simple, can give a lot of depth. I really hope you improve it in favor of developing builds and variety of playstyles. A lot of times, inflationlike games feels like there is only a viable build that you must follow in order to advance. This is my opinion, but im sure that even if this isnt your plan for this game you will make it in a way that i will love. This game have a lot of potential!