the game mechanics are good, i didn't find any strange bugs , the basics are there, instructions, level, boss, score, lose, win , end. The boss was very challenging, there is a good base for refinements,
as for critique i do think you could lengthen the levelplay more by spawning more targets or faster, so there was more time to get into the gamemechanics and eased more into the final battle, also the connectivity between things feels a bit rushed, first you have to keep targets from bouncing into fire, then you have things falling on the ground, then you have a boss who keeps floating into air.
but good start overall, keep at it!