Simple but wonderful!
It was very reminiscent of the early 2000's flash games where there was a large trend in innocent characters committing terrible crimes which was always a humorous trope.
Only areas for improvement is that I don't really feel there's a defined goal other than kill, adding a simple scoreboard or timer to add a sort of arcade element where you beat your best scores or time could help make the game more complete.
If you wanted to take it further you could introduce more elements such as leveling up, learning new moves, and evolving which I think could lead to a very fun game!
Overall fun concept with good execution!