“The first draft of anything is shit.” - Ernest Hemingway
Hemingway was right, and for me personally, I finally understand why.
As any Writing 101 will probably say, it's one thing to have the inspiration and total image of the story you want to write in your head, and quite another to make the whole thing work on paper. Transferring anything from your mind to the visible and tangible medium of choice—be it the canvas, the page, the camera, the computer, etc.—takes a lot of effort if you want to do it effectively.
For my writing, I've come to see the first draft essentially as a placeholder for every single rough idea I have, while is then surrounded by my feeble attempt at unifying these ideas with “cohensive” storytelling. Working through a first draft involves coming to terms with the fact that the medium, like any other, has its limitations. For example, writing involves the sole usage of words and their arrangement on the page (the latter is most especially important to poets, but occasionally you'll find unconventional sentence and passage structure in prose).
This is another reason first drafts are so scary. It's here that all writers receive the terrifying realization that they don't know entirely what they want to say, nor how to actually say it within the medium. This uncertainty and vulnerability is what probably scares off so many aspiring writers, even—or especially—the most talented ones.
This is a necessary evil that all writers must face. Some writers are better at handling it than others. Once the writer can actually put SOMETHING on the page, then they can shape it and rearrange it and add to it and subtract from it so that the final product fully expresses what they want to say. It's like dumping all the colors of paint that you know you want directly onto the canvas, and then having the supreme luxury of being able to manipulate the colors to the areas you need them to be to having your ultimate painting, your ultimate statement.