I think many readers think that the story that they read is the first incarnation. Well, for most of us, it isn't. Beginnings are the most difficult to write because the writer has to:
1) engage the reader
2) introduce characters to engage the reader
3) give enough back story so not to lose the reader's attention
Notice the common denominator? THE READER.
As much as writers are delving deeply into their own personal psyche, they are also tempering their story to engage as many readers as possible. Writing in a particular genre and style also play a part in the equation. You don't want to pick up a thriller and have it start with how horrible the main character's childhood was. You want to start with action.
Writers not only write, we rewrite . . . A LOT.
About three years ago, I wrote GNOME. During my querying phase, which lasted for over a year, I rewrote the beginning of the story no less than five times. AND this was after I had edited it prior to the query process. After I decided to query FAERIE, Summer 2010, I put GNOME aside. During the fall of 2010, a friend of my self-pubbed and was doing quite well. I knew I would have a tough time selling my novel (it's a middle grade and her novel was a romance--different audience, and romance writers have been electronically publishing for numerous years), but I thought this story deserved a break so I had another writer friend look at it. She thought the beginning was slow. 10,000 words into the 40,000-word story slow. I cut 1/4 of the story and rewrote it into 1,200-words.
GNOME is now lighter and leaner.
As a writer, you have to make the hard decisions--for the good of the story. So many newbie writers feel that their words are gold and refuse to buckle under pressure because someone didn't 'get' their writing. There's a reason many people don't 'get' your writing and many times it's because it is weighty with backstory narrative and information dumps.
I'm not saying that you shouldn't write the backstory information--you should, BUT DON'T SHARE IT WITH THE READER. They don't care. All they want is to get into the story--so start the story with change. What makes your character's happy little world go into Hell-in-a-Handbasket? So what if your main character had to lie about their age to get a job at fourteen to support their drunk and psychotic mother. This is backstory. This builds the characterization of the main character (MC), which in turn, effects the MC's decision making and actions/reactions to various circumstances, but the reader doesn't want to read about it.
Every writer has their own way of writing. Some writers write X# of pages every day and edit the previous day's pages before they move on. Other writers write the first draft all the way through, discovering their characters, plot, etc as they write. And then when they know enough about the character's they can tweak and edit the story based on their new knowledge.
Some writers will write detailed character sheets, while other writers 'wing it'.
Not every writer writes the same way. This is a good thing, because everyone has a story inside and the difference lies in how you tell it. Just remember, that a first draft is 99.9% NOT good enough. Dig deeper into your characters. Read your genre. Cut all the superfluous words. Tighten excessive wordiness. Chose your words carefully. As a writer, you are a wordsmith. Treat words with the proper respect and use them well.
Remember, only YOU will have the passion to write YOUR story.