I have no idea how much of this is already provided by Unreal Engine, but either way It's really impressive how much you managed to managed to accomplish as a newbie and in only half of the allowed time.
Making a fast paced 3D platformer FPS game is quite the commitment that you don't usually see in this game jam.
There are of course things that could be improved. The thing that stuck out to me the most is that the terrain felt somehow haphazardly placed. I could go somewhere and do a big jump or a wallrun but I couldn't smoothly chain these movements from one section to another.
Throughout the game it wasn't apparent to me how much energy I had or for what reason I died. I don't know if there was an HP or energy bar but nothing stuck out to me.
Congrats on your first game jam submission!