Many believe that God is the universal creator of all living beings but there's no one special God in Buddhism. In fact, there are many Gods in Buddhism and yet they are not creator. We ourselves are the creator of our own existence in this world be it as human, gods, demi-gods, animals, ghosts and hell beings by the law of karma. All of these realms are subject to change and evolution which are non permanent in nature.
If there is God, why is there the disparity, sorrow, calamities, suffering, differences in each and every being? Shouldn't there be happiness all round? Well, it is not so as we all can see. It is our own deeds that create both positive and negative results according to the law on cause and effect.