The fly is seen better as a divine creation, which has been corrupted from that initial purpose; e.g. it now carries disease to other life forms and is affected by disease itself and gene deterioration through gene mutational load-e.g. the buildup of harmful mutations.However, it is also unknown how many "kinds" of flies there may have been at the initial creation. Both "kind" and "species" are groupings. It is amazing that God brought the animals to Adam for him to name.
See section on Issues in Creation and Evolution then tab Adaptation/Variation on this website for more information.