This mechanic of going from room to room reminds me a lot of Binding of Isaac.
And I don't see the problem of being inspired by other games to make your own. But I think your game needs something more to make it more attractive.
I don't know much about game development, but this is just a piece of advice IMHO that if you do a mechanic like moving from room to room it doesn't keep the player going in one direction (up) but it could also move from left to right and of course down. That would make it more interesting because it would feel like being inside a dungeon.
And the second thing is that you try to give the character and the enemies more fluidity. I don't know if the others think the same but I feel a bit slow. The same goes for the energy balls that the protagonist shoots.
Please don't take this comment badly, it's just my humble opinion. And with the graphics and the time you put into this game I know you can improve it.