This zombie is supposed to be one of the feared residents of the City in the Sky, and the zombie had died amongst the other citizens when the City fell, but not one of the citizens had stayed dead. They had all awoken due to the strange power they had, which turned them into mindless zombies, and their only desire is to kill the people who had caused their majestic city to fall.

Entry for this event: https://www.planetminecraft.com/events/mobs-of-minecraft-reimagined-community-event/entries/