I doubt that “the Norse religion existed already in 500 BC, and probably goes back another 1,000 years prior to that”
The Norse religion is the specific Germanic version of the standard Indo-European religion with some flavours like hell being of Ice, like Ragnarok etc. There isn’t evidence of this as far back as 500 BC
What I find fascinating is how the Indo-European pantheon evolved.
The most primitive gods - that of the Wind, the Sun and fire are common to all the branches of I-E
In Hinduism these are Varuna, Surya and Agni. In the pre-Zoroastrian Irani religion these are Varna, Surya and Agni. In the Slavic religion these are Wiatr, Slonce and Ogien. Similar gods we find in Italic, Greek and Germanic religions.
The hittite gods seem to be these same
But the change seems to be around 200 BC for India, 300 BC for greater Iran and later for the others
In greater India the IE gods get merged with the Dravidian gods and the Vedas are downgraded and we get the Trimurti (Shiva, Vishnu, Brahma). In Iran we get the prophet Zoroaster who raises Agni to Ahura Mazda.
In India the original two families of gods - the Asura and the Devas fight and the Devas win, while Asura are relegated to demons. In Iran the Ahura and Daevas fight and the Ahura win while the Daevas are reduced to gods of the hearth.
In the Germanic regions these are the Aesir and the Vanir
In the Greek and Italic we have the original 2 god-families separated into Titans and Olympians - though this seems to be more the influence of Sumerian and perhaps Semitic religious pantheons.
It was a few years ago but I don't think I said that.
I said that the current crop are posers who have no idea what their worship requires at least in the historical sense.
I would give you a detailed run down but I have to scram if I want to be on time for evening service so let me know if you want to talk more about ancient religions.
One of my favorite subjects.