Thank you for the info lol, this is not entirely my first game. I wanted to add more weapons but the time was a bit limited, I only had time to fix most game breaking bugs nearing the end, lol if you couldn't kill the first boss I'm actually happy because I think that guy has a mind of it's own, sometimes he moves at the right speed and sometimes he just floats around, I struggled to find the problem, but I'm glad you got the right playthrough.
To be completely honest, I don't think more weapons would have solved it. It's a fundamental design issue, and you'd have to dig into the design of the second to second gameplay. It's about making the player do things that are interesting to them. A bit of a more full explaination: link to not clog with massive video embed
So very roughly I'd say there are two parts to making a game; the idea and the polish. Let me try a cooking analogy: the idea is like your ingredients and very rough instructions like "heat it" or "kneed it". Polish is figuring out the right temperature, the right time in the over, the optimal size of the portions. But fundamentally, those ingredients are the core. Everything else is just making the best that you can with those ingredients.
What I can help you with is the polish part, not the idea part. I think that the game lacks a (from a player perspective) compelling way of interaction. Like what is the fantasy of this game? What am I doing? That core interaction is the core of the game. It's often connected to a test of skill. Celeste is at it's core a game about timing button presses, and a bit problem solving. Sekiro is a game about remebering patterns and timing button presses. Factorio is about understanding systems connecting together, and handle the changes that come with upscaling.
Meat arena is about pressing W while looking towards an object, then pressing a button to pick it up, looking at the boss and then pressing a button to throw the object. That's the fundamental gameplay. That's the ingredients that Meat arena brings.
So I don't really have a suggestion, I think my suggestions would be a new idea, or new ingredients if you will.
Takeaway: think about what the player is actually doing. The button presses. What makes those button presses interesting?