@Desert Fox @Skies @Taygibay
Basically Vedas have many deities because the Vedic religion divested more individual moral authority on them, in effort to give a nuanced message on why even set up a core moral authority and understanding over time (which in essence turned out to be Upanishads). In a way the almighty god, the Brahman, the force of the universe personified in the sound of OM... (and the conclusion of the Vedas itself is really God and Truth are the same thing) set up a process (Samhita i.e underlying esoteric discourse) of how do moral debates and struggles over time (in conflict with: themselves, immoral forces and even the larger layer of absolute Truth)...reveal God in the end.
Take the concept of Indra. The continued story (in Vedas and post-Vedas) is his struggle against the evil/disorder/ego personified by the Asuras. That in itself sets the notion that there is Good and Evil and that the Good must be fought for and preserved. From only that does the understanding of a higher force than Indra himself comes (i.e Indra himself is found within this battle, who surveys it from above and what is the purpose?). This is also why later Indra becomes (after conclusively defeating the Asuras and they become largely irrelevant in further stories) fully invested (in Upanishads and also many Puranas) in asserting his overlordship on mankind because of his Ego..i.e removal from greater truth...becoming the very thing he swore to destroy (the commentary on Indra being a fallen hero is quite significant one in Hinduism).
Any humans trying to achieve the greater truth beyond him (Indra) is a threat and must be swayed and deflected from it. Hence in all post-vedic stories... he sends the seductive apsaras, promise of kingdoms (so man may have dominion over other men, much like Indra revels in in larger scale) and material wealth and the overall message that life is just a material thing to be enjoyed....to each and every greater truth seeker on Earth (the sages, ascetics, warriors, thinkers, philosophers seeking more truth and purpose beyond just the material world). But the few of them find the greater truths anyway, past all these temptations...some dynamically use to defeat Indra (or another worthy quarry) himself in some way and become a scale of untruth themselves in that process/desire (setting up the absolute Truth to defeat them in the end again)...some simply revel there statically (the purpose of Buddhism etc)....others still realise there is no ending for the soul to the search for ultimate truth itself, just like infinity cannot be reached (but the process is itself what matters the most...to create order out of disorder...and that itself becomes the ultimate truth rather than an end defined goal etc)....i.e that order and only order leads to Truth itself.
Hence that is why the forces/deities in the Vedas are symbolic largely to the greater absolute truth (Brahman) that is established in the Upanishads (the refined underlying meanings/debates of the Vedas) and following Puranas. In ritual practice, the myriad of powerful deities in the Vedas were subsumed by Creator, Preserver and Destroyer (since those are the fundamental processes in all life, which is the basis of how we even experience this all in first place) who were generally just hinted at esoterically in the Vedas...and these powers are subsumed by the larger reality/truth/purpose that is the Brahman (or female equivalent of Shakthi).
Why did this process (from many to a few to three to one) happen? Simply put, humans are stupider and weaker now overall (in every way imaginable)....so things have to be simplified for them to hold onto morality wise overall (of course there are those that are exceedingly righteous..i.e heroes despite the deteoriation...but they will find a way to establish good in society anyway). Before there could be many competing conundrum of moral forces (in say Vedas) simply because humans were able to organise intuitively and find the common single message/authority of one single truth, having just awoken to their higher consciousness, the raw nature of civilisation was very much in their souls still. It is seen in the progression of the Yugas (and why Vedas were even split into 4 pieces just before Kaliyug the current and last one started).
Now as civilisation deteoriates, the moral system for truth naturally is propelled to be crystallised/refined to such extent such that it imprints in large enough audience to begin with...because humans have now removed themselves more and more with their own ego/materialism, and thus cannot as readily access truth from perceived cacophony, it has to be crystallised and given as simple as possible (and then the few astonishing ones can explore deeper from there etc). It is an interesting inverse relationship imo.
You see Hinduism is just a longer drawn out purpose of how humans found meaning from that which they saw around them and then crystallised it....recognising that which is good is fundamentally which creates order....and the opposite for evil....harnessing concept of the Hero (since the good is embodied and personified most readily there).
We see similar parallels with the story of Garden of Eden, the great flood and the Exodus in the Abrahamic world (their earliest extant stories with the concept of the hero).
If you do have some time to spare, please go through this (it gets really interesting around the middle, and explains a lot of what I am trying to describe here more generally as it applies to our core psyche and self-realisation of existence/purpose). It also touches a lot of what I was trying to explain to
@Mage, he should watch it too i feel:
