According to history and all that is Hinduism (sanatana dharma) a religion or just a mythology. I ask this because Greek mythology and Hinduism have a lot of similarities so of one of them is a mythology shouldn’t Hinduism also be a mythology. Another thing, is the Indo Aryan migration theory .According to historians, the Indo Aryans migrated into India and mixed with the local dravidian population. They brought the vedas and sanskrit. And the two cultures mixed. If this is true then how can Hinduism be true if its two different cultures combined? Also, Why did gods like Indra become minor and shiva, vishnu, and brahma become bigger in one of the vedas ?( I forgot which one) I was also wondering about Indo European history and was hoping someone could explain.

Note; I used words like religion and culture to make it easier to understand. This is not hate, im a hindu and these questions were on my mind and I want answers so I can build my faith.