It's a fun game for being made in just one day.
It seems like you had a bit of a planning issue. To show off the going up/down levels mechanic, which is core to the theme, a good starting point would've been to make at least two playable levels, just with different enemy sprites. Then use a simple transition to move between the levels, even a cut to black would be fine. After that, if you had spare time, then think of adding cinematic camera animations and slo-mo effects.
Good luck on future projects!