This is great. I liked how you styled your Itch page to put you in the right mood before it loaded. Overall it's consistent with the theme, and there were some nice _a-hah!_ moments as I discovered more of the mechanics. The notion of switching the kind of character you are in order to move throughout the level reminded me of _Gianna Sisters: Twisted Dreams_, and I like that you contextualised it with dialogue.
I think you did the right amount of levels for a game jame - I wasn't bored!
The only thing that confused me was that trading life for items didn't seem to make sense thematically - you didn't use the grey robe, you used the fact that you were old to tell a story. Maybe this could be resolved by just changing the item names to better indicate what is going to happen. At first, I assumed there might be a penalty for buying the sword since it _cost_ life, and I didn't think that you'd be able to switch back.
The only thing that I think could be improved as a quick-win, mechanically, would be that I expected to be able to trap the guards or kill them on the spikes/fences when I flipped the switches, but they just slid out from under them.
Really neat, and it benefits from its simplicity. Good job! :)