Every voice is unique. The words we use, sentence length and structure, pacing and rhythm, tone, our use of description or lack thereof. You’ll never find two people who talk exactly the same. We all see the world in a different light, and the way we describe it to others is defined by our background and life experiences.
Every first draft will turn out differently depending on the writer's process. Some people outline every little detail beforehand, while others go with the flow. There are no set rules to follow. So, the only goal you should have in mind is to finish the story.