>Arceus is particularly based on a creator deity, present in many world cultures. Arceus's stance and general form are similar to Egyptian bull and calf idols, particularly Apis. Based on its official artwork and attack movements in the 3D games, Arceus may be modeled after a horse. The arc on its back may be inspired by the circle arc used to represent reincarnation in Hinduism.
The conception of the first god might be influenced by the Shinto gods Kunitokotachi and Amenominakanushi, who summoned Izanami and Izanagi to create Japan with the spear. It may also be a reference to the qilin, a Chinese mythical creature. Its myth is nearly identical to that of the Pangu, the Chinese creation deity. Arceus may also represent or be inspired by the bodhisattva Avalokiteśvara, who, in Buddhism, is either pictured with eleven heads and one thousand arms (the latter of which is mentioned in Arceus's Pokédex entry) or in a white, four-armed manifestation (which could look similar to Normal-type Arceus).
--Straight from Bulbapedia.
Thus, there is not "one" inspiration for Arceus. It seems to be a mixture of multiple Asian ideas and concepts merged into one.
In addition, Pangu was a Cosmic Giant who erupted from a Cosmic Egg. He later died and parts of his body became the various parts of the universe, like the clouds, mountains, and so forth, if I recall correctly.