Why are there so many Gods and Goddesses in Sanatana Dharma?

In most religions, there is usually only one God. But in Sanatana Dharma, we see thousands of Gods and Goddesses being worshipped. Why is that?

There are about 400 rivers in India — Ganga, Yamuna, Kaveri, and many more. Can we say there is only one river just because all of them carry water? No, right?
Do all rivers behave the same way? Some are very long, some are short. Some dry up in summer. Some flow stronger in summer due to melting snow in the Himalayas. Some flow calmly, some rush violently. Some flood, some don't.
When this is the reality. Can we still say there is only one river?

Sanatana Dharma is based on the Vedas. The Vedas are not man-made; they weren’t written by any person using imagination or thinking. They describe the universe exactly as it is — not theories, not guesses, not human ideas. There’s no over-simplification, no hidden agendas. Even Indra, the king of Devas, is sometimes criticized in the Vedas. They even mention that the Devas sometimes ran away after being defeated by Asuras.
Can you find such honesty in any other religious text?
The Vedas tell the truth exactly as it is — without hiding, or twisting.

Every mantra in the Vedas is linked to a specific Devata. And even the same Devata appears in different forms.
Take Shiva for example — we pray to Dakshinamurti for wisdom and to Uma-Maheshwara for marital happiness.
Though all are humans, we go to a doctor when we fall sick. Not a lawyer, right?

Why did Bhagavan take ten different avataras? Because each avatara had a different purpose.
Are avataras just imaginary stories? No. Even today, places linked to Rama and Krishna exist. Archaeologists have found proof from those places.
Rama and Krishna lived in different times and for different purposes. So, what’s wrong in worshipping them differently?

The Vedas say — every ray of the Sun is a mantra, and each has its own Devata.
Even though Paramatma is one, He appears in different forms based on different situations and needs.

Water, ice, and steam are all the same substance — water. But you can’t do with steam what you can do with ice, right?
Both father and mother are humans, but our relationship and behavior with each is different.
The Vedas declare that in the beginning, Brahma split Himself into many forms. So why deny diversity?

The Vedas see Surya, Chandra, Vayu, and Agni as Devatas. We see each of them differently around us — then why shouldn’t we worship them differently?
Today, they are still worshipped under different names — Surya as Narayana, Agni as Rudra, and so on.

Ramaswamy Sastry and Vighnesh Ghanapaathi