I suppose everyone wanted to ask this question as who experiences gods? when there are no gods. In other words why plurality in the name of God. And how do people relate plurality of God with Philosophy when they are aware of the concept that this plurality mearges with Singularity. It means to me that we are searching for Unified Theory.
To do this we have to have a Language that will discribe the unification. See, in the world of Object-Oriented Programming, the entire system is consider as Collection of Ideas(Class) and their manifestations (Object). To understand the concept fully the student is taught to see the world around in terms of Classes and their manifestations. This is done with the help of a Language that is called as UML Unified Modelling Language. It unifies the Ideas present in Human mind/intellect and the Computer Program that gets executed. There are several ways in which people Model their Ideas. Every Organization makes its standard for it. But every Organization at the end must reach to a stage of writting correct and desirable software out of its UML.Exactly is the situation in the field of Vedic Sanskriti. God is consider as Abstract Class and the manifestation of this Class is done in many ways to a YogSadhak(YogStudent) reffered as 'Gods'. I suppose the only missing aspect today is the methodology in gaining knowledge. Jnaana yoga is all about uniting with Jnana. This is done by practicing Yog(Patanjali) in correct and disciplined fashion.
Actually,Vedic sciences classifies stages of YogSadhak(YogStudent) in following manner
In each stage some significant changes happen with the student.To notify those changes some Models(gods) are attached with every stage. These changes are noted in the form of Model to indicate the correct direction. Every YogSadhk should experience it in the similar fashion. The stage is identified by the model perceived by the student. These Models are reffered as gods. In each stage there are one or more Models a student perceives. That is why plurality.
Pruthvi in Sanskrut means to classify and identify . It is a stage when student learns how to see things clearly which is a default stage of every human being.Hence no need to tell him what is what. Human being by default learns to see the things separated. That happens in the Prithavi stage of the Sadhk.This is the begining stage of the Sadhak. Hence no significant things are there in this stage.Hence no gods(model) other than Mother as god, are attached. Mother is what is the first object Human being separates without much problems. Hence here who so ever wants to be in this stage only should consider ultimate source of Knowledge as Mother only.
That is why Vedik people considerd Prithvi as Mata.
Aap which is next to Prithvi stage means Water the color of which is considered as White hence God of Aap that is Shankar is attached with White color. This is the stage where Sadhak experiences the effect of activation of his Serpent Power(Kundilini Shakti). When Kundalini Shakti gets activated Sadhak sees lots of Snakes around him, he as well experiences the effect of strong heat inside the body so much so that he always wants to be with Water only. The Lord Shiva is to indicate that stage of the Sadhak. That is why He is shown with White Gauri,White Ganga,Snow White Himalayas,Snakes around the neck to soothe the effect of the Heat genarated. This is the stage where Sadhak as well expereinces some eternal sound continously. This is the reason Damaru is shown with Him. In this stage White Moon is also seen by the Sadhak, that is why Moon is shown above the Lord Shiva. This is the stage where strict disciplne is required so to indicate the alertness it is shown that Nandi is constantly watching the Shiva Sadhak. Nandi is a derivative of the word Aanand. This is to indicate the pleasure or Aanand the Sadhak is likely to have if he overcomes the stage of Shiva. This is the stage where MuladharChakra is activated. The person is activated form his default stage. This experience is really joyfull and Sadhak behaves in the blissfull state only. That is why Shiva is depicted as most Joyfull and innocent god who likes white Bhang a kind of the sedetive that makes to enjoy a state you are in. Since this the first stage after default,some times Sadhak tends to loose his patience. If it is not controlled and disciplined, Sadhak may destroy himself that is why Shiva is shown as Destructor. It is respected belief that a person who is dead has transformed to a stage of Aap and that way has mearged with Lord Shiva. That is why in India in some part people still write KailashVasi against the name of the dead person.This is the reason why Shiva Murti is there in Hindu crematorium.Hence it is customary to accompany a dead person in White color dress.
Tejas, next to Aap, is Fire or Light hence color of gods attached with this stage is Fire color that is Shenduri color. Gods like Ganesh,Durga are indicators of this stage.In this stage Student acquires knowledge in a speed of Light!!! That is student becomes very Intelligent. Hence Ganesh is considered as Lord of Vidya(Education). In order to reach to this stage Sadhak has to crosss the Aap stage. So from the Aap stage only Tejas can take birth. That is why Lord Ganesh is shown as the son of Lord Shiva. At this stage now Sadhak has overcome the problems and anxiety of Aap stage so he becoms more relaxed and tends to be acquiring the knowledge in the speed of Light. His entire structure becomes enlighting but the Body in this stage will be calm and quite. That is, it becomes more Sthula. Sadhak first time experiences the sound of Omkar from within the body. All this is depicted in the Lord Ganesh. Omkar sound is shown with the help of Elephent Trunk. To have the sound listening capacity and level headed approch Elephent Head is shown with Lord Ganesh. This is to simply indicate the attributes that have been gained by the Sadhak in this stage.
Now once Sadhak acheives the Tejas stage, more study(Sadhana) is required for the next stage. Vayu is the next stage. Vayu is next to Tejas with the color of Tejas but it is a stage where student achieves knowledge in speed more than Light hence they are shown with tail. Lord Hanuman,Narada,and Garuda are indicators of that. Here the Yog Shakti goes beyond the speed of Light. Modern physics and Science is yet to cross the limit of Light successfully.But the YogSadhak in the stage goes anywhere in the Universe.He attains the state where he can experience the lightness in the body. Time dimension is no more relavent in the stage. He has to have the attributes of previous two stages that is why Hanuman is shown with good physical body and sharp intellect. The Sadhak at this stage will always be good follower because by this time he has acquire and understood the futility of maintaing identity. That is why Hanuman and Narad and Garuda are considered as Bhakt rather than god themselvs.
Aakash is next to Vayu the ultimate stage where the student aquires knowledge of every possible aspect of life that is Brahama. Basically it is said the Brahama stage is beyond textual or any other description and to show the Nothingness or Void it is compared with Space or Sky. This makes the stage to have a color of Sky which is more black than white in Black & White. Lord Vishnu is indicator of this stage and Lord Ram and Krishna are incarnations of Vishnu. Hence the color of Ram and Shyam is Sky Blue. Since the Sadhak by this tries to be more with Brahma and hence the Yogabhyas ends here. Sadhak by this stage activates his Kundalini power to the last that is SahastrakarChakra. That is why it is belived that a Sadhak will control his Sahatrakarchakra. This is indicated by Sudarshanchkra as wepeon in the hands of Lord Vishnu. In this stage Sadhak has fully controlled his Kundalini(Serpent/Snake) power hence Lord Vishnu is shown sleeping on the beds of snake.
This is the Yogic Truth and answer for the plurility of gods. So this clearly indicates that Vedic gods have been depicted as Modelling of the stages a Sadhak will undergo in his Yogic persuasion. Vedic gods are not mere metaphor for 'Good' and 'Bad' or 'Sur' and 'Asur'. The concept of Swarg and Narak (Heven and Hell) is again Yogic only.
So the essence is that Vedic Gods are experienced Gods by the YogSadhak. There are many such people who will confirm such experinces. They are scattered through out India. Since so much of Sadhana, makes them to enjoy in secrecy. We dont find or recognize them. One can also get this, subject to the strict aderence to the methodology of the YogSutras and YogSadhana.
This was describe in the typical Vedic fashion in the Vedic Books. Over the period, people lost the correct aspects of the YogScience and the result was that people started beliving them to be the Gods in the Vedic Dharma. To fall in the Bhakti Marg is the most easiest and simple way for the general masses in this part of the world. That way element of Shardha crept in. Kundalini can be activated in the true devotional manner as well. Meera /Radha are indicators for that. So people belived that this way we can reach to the ultimate state in the Knowledge searching. Bhakti can activate Kundalini only in the first stage. It makes a Prithvi Sadhak to go in to Aap Sadhak only. To expeirence other stages one has to go in the regular and correct way of YogScience. But Bhakti was natural for the masses in this part of the world. These were ready Models available for them to attached their Bhakti and Shardha. Hence some other cult with in that also started. That is how PolyMorphic Vedic Sankriti evolved. But basically it all started to indicate the models of the Ideas a Sadhak expeirences in his YogSadhana.