Glad you liked the game. I inspired myself of 3D Mario games where enemies are more seen as obstacles than real enemies, so don't expect incredible combat in the future. It will stay simple, with a little bit of variety with them, but that's all tbh.
To provide an idea on what I think makes combat work better in 3D Mario games, I'd say that a big part of it comes from how the attacks function. A lot of Mario combat with basic enemies is integrated into the movement. The slam attack in this game works pretty well like that, but the basic attack is very fast and effective at just nullifying the enemies. I'd maybe consider giving it more of a cooldown between swings to require some form of timing. A lot of Mario enemies also move in unique ways or do interesting things which makes dealing with them a bit more satisfying. It's not really like it's bad right now, but it's like the other guy said where it just isn't really engaging the way the rest of it is. I do think some tweaking could make that happen without making enemies feel like a major focus.