The first draft is just that: a draft. You get your story ideas down in sequence. You do not need to get everything perfect: scene sequence, character, dialogue. All that comes when you go back to editing. First you write.
At this point you don’t need to write well, just get the story down.
The first draft helps clarify where the holes are in your story. Need to know a little more about how a character reacts to a bad situation? Don’t know exactly where in the palace the room is? Don’t know what sounds are in the background? Mark those places and come back later.
The aim of the first draft is to get the entire story from beginning to end written. Months of research, plot outlining, character development come to naught if you do not write the story. So your goal for the first draft is to get the entire story written. Writers write story.
An idea is not enough.
A plot outline is not enough.
An intriguing character is not enough.
The first draft is the first bare bones of the story. Does it all hang together? Do the sequences make sense?
Editing and writing are two different processes. Writing comes first.