Looks like a good start. The next step is to use a circle collider so your ball will bounce at angles. Also you might want to switch the player and back wall positions because players expect the action to go from left to right.

This is a good start but needs a lot of polish.

The first thing is the intro music felt really loud even thought my computer volume was low. The music was generally loud compared to the SFX. There needs to be volume controls.

The ship movement feels somewhat slow and could be increased a good amount and still be fun. Also the player projectiles could be faster to make the game feel "punchier". There needs to be more feedback when the player gets hit and would be an appropriate place to add a bit of screen shake (don't overdo it).

Losing life needs some kind of animation to draw the player's attention to the heart going away. Generally the light purple on dark purple life bar is confusing, maybe have it start green and fill red as you lose health.

Some of the enemies spawn on top of each other so maybe add code to make sure that doesnt happen.

It is confusing sometimes which objects are in the background and which are in the foreground so maybe do something to further distinguish the layers like a blur layer or decreased saturation or both.