The cover art references the popular video game Fortnite: Battle Royale.
The female character's design in the cover art seems to be inspired by the Power Chord skin from the aforementioned game, while the male character's design is based off of Gammer (the original artist of the song)'s real life look.
To find a remix, find the artist's name under the alphabetized list. All of the artist's remixes are listed with their name. For example, Morgan Pages's remix of 'Downhearted' would be under the 'M' tab, since the artist's name begins with the letter 'M'.