A group of people building gingerbread houses.
More than one person is working on edible buildings.
A group of people means there is more than one person, and building gingerbread houses means working on edible buildings.
A group of people means more than one person. Gingerbread houses are edible buildings.
A group of people building gingerbread houses so there should be more than one people and they are working on edible building