The Zelda-like Tilesets and Sprites were created by ArMM1998
Source: https://opengameart.org/content/zelda-like-tilesets-and-sprites

They are licensed as 'Public Domain':
"You can copy, modify, distribute and perform the work, even for commercial purposes, all without asking permission: http://creativecommons.org/publicdomain/zero/1.0/"