Hello there!
Thanks for the feedback! I'll have to consider adding some sort of visual flair to my HUD to make it more clear when weapon items are picked up vs instant-use powerups like health restoration or invulnerability.
As for having health bars on the enemies, I was worried about making things too crowded visually (like possibly having health bars run into each other or draw on top of each other) and wanted to keep it fairly simple, like a retro game. Maybe I could try to differentiate the sprites a bit more, or add enemy health values to the Travel Guide section of the menu.