Agni is the symbol of Paramatman (supreme god) and all the other gods are different aspects or manifestations of the same Agni. According to many scholars, the most appropriate Vedic symbol for the supreme position among the innumerable Vedic gods is Agni. Agni is the fire principle that shines in the sun and also the one who carries our offerings to other gods. He is the friend of man and mediates on his behalf. He is the symbol of wisdom, knowledge, compassion and lordship. That was the reason he was worshipped by three thousand three hundred and thirty-nine gods.
Three thousand three hundred and thirty-nine divinities have worshipped Agni; they have sprinkled him with melted butter, they have spread for him the sacred grass, and have seated him upon it as their ministrant priest.
Suktas like the one which begins with ‘Tvamagne prathamo angira; You, Agni, were the first Angiras rishi.’ (Rig Veda 1.31.1) and the one which begins with ‘Tvamagne dyubhistam; You Agni pure and all-radiating.’ (Rig Veda 2.1.1) portray Agni as the embodiment of omnipotence and omniscience. The god Pavamana Soma, in fact, is Agni himself. Soma is symbolic of Brahman and realizing Pavamana is nothing but realizing Brahman.
In the Vedic and Vedantic tradition the ultimate supreme Reality is designated (though it is beyond description or definition) as sat-chit-ananda. According to the Rig Vedic sages Agni, Surya and Soma are the symbols of sat, chit and ananda respectively. In other words Agni, Surya and Soma together constitute Satchidananda.
On the other hand, in some verses the rishi says that the same god (Agni) appears in various forms as Indra, the giver of rains, Vishnu, who, dwelling within the hearts of all, protects the world, and so on.
Agni is one though ignited in various forms, the one sun rises in all the worlds, the one dawn lights up all this; the One alone has become all this. (Rig Veda 8.58.2)
In most of the hymns referring to various gods such as Surya, Agni, and so on, we can find the underlying divine principle to be the same Paramatman. The glory of the various gods and goddesses is, in fact, the glory of the same divine Reality.