Every Hindu Gods are Manifestation of BrahmAn. Even though BrahmAn alone is the reality BrahmAn Manifest himself in the forms of Devatas as cosmic forces to sustain the universe. Universe is Complex. Universe is complete harmony. Vishnu mortal Avatars validated this. Advaita alone is not enough. Advaita, Dvaita and Sankya Vedanta go all together. They are inseparable.