Let me just say right off the bat, writing a first draft has been described as word vomiting. In Bird by Bird, Anne Lamott says every first draft is shitty. This is truly the only way to look at it. Anything else will leave you feeling inadequate.
It’ll never be what you first envisioned. That’s completely normal. To expect it to be otherwise is setting yourself up for disappointment and possible failure. It seems to me that the most difficult part of the writing process for new writers to learn is to be at peace with the halting messiness of the process. They have this idea that from the very first page they will pour out beautiful prose, covering the blank whiteness with their brilliant cathartic vision.
Then they are hit squarely in the face with reality… a shitty first draft. And they give up. Or they get into the endless 3-chapter-loop, revising the first few chapters for years until they finally give up. Maybe they start another novel or give up on writing altogether.
It’s not because they couldn’t write. It’s because they couldn’t allow shitty imperfection and messiness. Well, guess what, that’s the way it always is, both in life and in writing.