If Hinduism as practiced is not polytheistic, then the word has no meaning.
That is precisely why Hinduism is so interesting and unintelligible to me. There are local or popular cults worshipping any number of gods or deities. There are those who believe all those gods or deities are simply the manifestations of a supreme being. I think there is even a branch which is somewhat atheistic. Maddening, trying to sort it out.