using the /biomefill command with my custom biome

Datapack Newbie here, I have been following along with Waffles Are Better's data pack tutorial for making custom biomes. I dont want to make my biome in a new dimension so I have just been using the .json in the biomes folder without the dimension folder. When I load my datapack in a world the game wont identify my biome in /locate or in /biomefill... Heres my folder layout and .json code: