Because every enemy has high health and you can only shoot in one direction, the window you can reasonably kill an enemy closes quickly, and you are discouraged from engaging with most of them; the most efficient strategy to beat a wave becomes selecting one enemy to destroy so you can loop around behind the enemy lines.
Once you do that, it's really easy to dodge enemy attacks, and at that point you just kinda twiddle your thumbs waiting for the next wave. Against most waves, you don't even need to kill any enemies to progress if you time your dodges well. The only waves you *must* shoot to pass are waves with silver eye enemies or a wave that is purely made up of the immobile flesh globs.If this is to be a shmup, shooting enemies should be essential to the gameplay. I think the game would be a lot more engaging if the enemies remained on screen until they were all killed (maybe reversing direction when they reach the edge of the screen), and if the player character could flip around to blast enemies (pressing "Z" to flip vertically or something).
That said, the controls feel great, the enemy designs are super cool, and I think you have a great variety of enemy attacks. It's also cool that enemy path movements are telegraphed and you can see which enemies will appear in the next wave.