People who argue about the polytheistic gods, who they were, if they have evolved or whether they are just archetypes do not really understand the mythological worldview. The ancient world was not clearcut. Anyone who thinks otherwise is living in a romanticized fantasy world. There certainly was no concept of cultural appropriation or idea that the gods belonged to specific cultures. The idea that a god belongs to a specific culture is ridiculous to begin with. In the polytheistic tradition the natural thing would be to look for similarities between the gods and if they found some that were fairly similar then perhaps they would be merged. For example when Gaius Julius Caesar wrote down his accounts from the battles against the Celts he compared the Roman gods to theirs. He could easily have said that they worshipped false gods and that the Romans did not. That is not to be understood as that he accepted the Celts – they were still seen as a barbaric people by the Romans. The same thing happened when they encountered the Greeks.
Deities would have their local variations and perhaps their own rites related to a particular region even within their own culture group. I read in a book review that it was a ridiculous idea to celebrate the Celtic holiday Imbolc when worshipping Hekate (not saying you should, I do not), because she was a Greek goddess. Well, she was not Greek, and her origins were likely Near Eastern, but the Greek adopted her into their pantheon. When you look at the historical sources of Hekate (and particularly her) then the idea of any kind of “pure” goddess goes right out of the window. The sources do not agree with each other and over time she would evolve into a more sinister looking character. The fact is that none of that is present in either Hesiod’s Theogony or the Homeric Hymn to Demeter from the archaic period.
That means that worship has not been static and not only has her character evolved between cultures, but also within the same culture. There is no reason to think that this not also apply to other deities. And why wouldn’t it? Look at modern practice of witchcraft for instance and you probably find as many types of different practices as there are covens. Even in mainstream religion such as Christianity there are many different approaches to their religion.
I therefore find that idea that there is a thing such as a pure idea of a god or goddess that belongs to a specific culture to be quite ignorant. Why could the gods not have revealed themselves to different cultures with different names? Why are there so many similarities between different mythologies in different cultures? Then again, if you are looking for any kind of logical consistency within the realm of mythology you are on the wrong track, because you will not be able to find it – even within the same culture.
In Håvamål from the Norse culture there is also evidence for that culture sharing is a good idea: “Only he who has travelled far and wide and over mountains knows.” In other words you do not learn anything if you just sit at home. If you travel, you are bound to meet new people and cultures to learn from.
The Night Spirit