How can I suggest happiness in a playground scene without showing any people?

An empty scene usually emphasizes absence, so implying “a happy child was just here” is difficult and can easily feel unsettling. A better approach is to suggest joy indirectly through mood and setup.

Use bright, cheerful lighting and a high-key look rather than dark or contrasty lighting. Warm color and a clean, orderly, visually pleasing scene will read as more positive. You can make the playground look inviting and ready for play, rather than showing abandoned items after the fact.

Avoid an empty moving swing, which can feel eerie. Instead, keep the swing still and focus on an attractive, welcoming environment. Toys can work if they look intentionally placed and playful, not dropped or lost. Shallow depth of field can add a dreamy, idealized feel if used subtly.

If you are open to including a subject, even without a child, a playful adult, yourself with a timer, or a smiling stuffed animal on the swing may communicate fun more clearly than an empty scene.

In short: emphasize invitation, warmth, cleanliness, and bright light; avoid props or motion that imply someone disappeared.