The specialization of structures within a cell, organs within a body and individuals in a society each open immense new possibilities. The occurrence of a new level does not obsolete the old. The old is built upon the new and the new continues to coexist independently as an essential thread in the fabric of life. If an attempt at a new level fails the old structures are still there to evolve in other directions or try again. The levels do not form a strict hierarchy.
Insect societies are less complex than an individual mammal is.
There is no final winner or absolute highest level although those at a particular level may have their personal prejudices. Nature is neutral on the matter and nourishes all who learn how to deal with her effectively. Each new level requires more resources for an individual. This means less diversity is possible and is a constraint on evolution. There is always a tradeoff between the advantages that come with more complexity of individuals and those that come with more diversity through more individuals.