Greetings, student! Welcome to GameDev.net. I read the title of your post and thought I could add something about what to prioritize in your levels. But then I read the body of your post and you didn't ask anything about levels. And by the wording of your final sentence (the question you're asking), the engine itself seems to matter to what you should prioritize.
What you should prioritize in your school project (I assume you're angling for a good grade) doesn't change from engine to engine. Perhaps your question doesn't need the last 2 words, “in UE5.”
What you should top-prioritize is the gameplay. Make the game action demonstrate the core gameplay, with responsive controls. You do need a UI that helps the UX, as a close second priority.