This story has some good bones, but the short version is incomplete. It feels like a chapter of a longer story instead of a self-contained one. Being marooned and struggling to survive is an excellent trope to work from and has a long history of good stories, Swiss Family Robinson, Tarzan, Lost in Space, Treasure Island, and The Cay, and I feel if you focused more on this instead of the scape it would come together much better within the restrictions of the challenge. Give it a few more passes, think about the themes and story beats you want to focus on, and go from there.
Keep up the good work.