[4] Musically, the song has been described as an emotional hip hop track that incorporates unique bass synth and electric guitar sound.

[5] Divyansha Dongre of Rolling Stone India categorized the track as a hip hop-rock release for its "strong sonic shift with the smooth insertion of bass synth" in the chorus.

[13] In Singapore, the song debuted at position 19 on the RIAS's Top Regional Chart in the issue dated February 4–10, 2021.

[17] In the United States, "Child" debuted at number eight on the Billboard World Digital Song Sales chart in the issue dated February 19, 2022.

[24][23] Lim Dong-yeop of IZM noted that, while the vocals are enhanced by the electric guitar, they tend to disappear when the rhythm section comes in.

As the song starts to build up, Mark wakes up and, when the "rockier" chorus comes in, the singer takes off running while he's chased by a group of strangers.

Regarding the fashion, Mark is shown wearing a "workwear-inspired layered look" at the start of the video, while in the next scenes he sports two other outfits: a plain white t-shirt paired with ripped jeans accompanied by a faux pierced eyebrow and a "glittering disco-ball" tracksuit covered in reflective tiles.

During the chasing scene, the singer is also shown wearing a "brightly colored" rainbow overcoat and a backpack that leaves trails of red smoke behind him.