Congratulations on completing your first game jam!
This was a competently made first game. The UFO mechanic is fun - although very hard (or maybe I am just bad at platformers). Do the UFOs sometimes change positions between deaths, or am I just gaslighting myself? 😁
For your next jam, have a look at things like jump buffering, coyote time, variable jump height, gravity curves etc. If you add them to your player object and make all the variables tweakable in the Godot inspector you'd have a polished 2D platformer player-controller that you can take with you from jam to jam!