creative writing - When to keep the passive voice and when to remove it

This is something I wrote:

The person was standing in the middle of the clearing, facing away from me. It was a girl. She was wearing a red knit hat, a white sweater, an a gray plaid skirt that reached right below the knee. What was she doing here, alone? I looked up, and realized she was gazing at a huge ancient tree. It was as thick and tall as a watch tower. Its branches resembled arms, and the leaves were so few you could count them with your fingers.

As you can see, that paragraph is filled with the passive voice.

So I tried changing some into the active voice:

The person stood in the middle of the clearing, facing away from me. It was a girl. She wore a red knit hat, a white sweater, an a gray plaid skirt that reached right below the knee. What was she doing here, alone? I looked up, and realized she gazed at a huge ancient tree. As thick and tall as a watch tower. Its branches resembled arms, and the leaves were so few you could count them with your fingers.

Did that improve readability? When to keep the passive voice?

Answer

On the language level: when you show a moment from a continuous, slow or unchanging process or state - showing that the process was in progress, or the state was such already when the observation began.

On writing level - purpose: when you want to induce the feeling of stillness, create image instead of action, describe state instead of activity. Also, similarly to passive voice, to instill the impression of helplessness, laziness or dependence: things are done to subject, subject is enduring/enjoying them. In this case though this is excellent usage for describing calm, constancy, peace.

Your first sentence was fine. The person stood in the middle of the clearing might imply "walked up to the middle of the clearing and stopped". she gazed at a huge ancient tree might be read as "turned her head to the tree and began gazing." The continuous tense leaves no doubts - the scene is very still. This creates a different, more eerie mood, an elusive feeling you lose when you chase after actions instead of painting the still image.