Hello scholars! I'm not certain this is necessarily a "history" question, but I'll shoot anyway.
So, as an amateur enthusiast in myths and ancient religions, I just spent the last day or so reading up on the idea of a "Proto-Indo-European" pantheon; a synthesis of the ancient religions of all Indo-European peoples, meant to emulate what the folks that came before all those disparate peoples split ways actually believed.
But, I couldn't find anything that felt solid or widely supported.
Websites like http://piereligion.org/ seemed jumbled and incomplete, despite offering a non-patriarchal model, which I would think would be the more modern approach.
and http://www.ceisiwrserith.com/pier/index.htm whilst presenting a more coherent picture, seemed to be more concerned with practical applications for modern worship and revival of the religion, which struck me as off.
And the Wikipedia page is a complete mess. So many of the deities mentioned as candidates for the various categories of PIE Gods are little more than stubs, if that.
The best I could find was this Reader on the topic from the University of Zagreb, but some of the stuff there didn't quite sit right with me for some reason.
If this was widely accepted theory, I'd have expected a nice chart that compares the qualities and names of all 12 or so Indo-European Linguistic Families' pantheons all organised on the Wiki page, with a nice page to describe each of the general PIE archetypes ("sky father", "grain goddess", "thunder-guy", "horse twins" etcetera).
So, should I leave this idea of shared commonalities between ancient Indo-European religions in the dust as a seductive yet outdated simplification,
or is this just a case of academics not presenting their findings well on freely available internet sources?
Benjamin Fortson's book, Indo-European Language and Culture: an Introduction (2004) is a pretty solid (to the best of my understanding) overview of Indo-European studies, mostly linguistics but it has sections on culture as well. Regarding a PIE religion, Fortson says the following:
"Nothing like a complete picture of PIE religious beliefs and practices is possible; in what follows, we can only give a sampling of the major divine figures, myths, and a few elements of religious ritual. On the whole, few divine names can be confidently reconstructed. Most of the familiar Greek and Roman gods, for example, have names of unknown etymology, and some (like Aphrodite) are known to be of Semitic provenance. Others, like Venus and the Germanic god Woden [Odin], have names that derive from Indo-European roots, but there are no deities in other branches with cognate names. Clearly the daughter traditions have undergone considerable change and evolution."
He does, however, identify a few reconstructable deities and divine figures: Father Sky (corresponding to Vedic Dyaus Pitar or Latin Juppiter), a male Sun deity, a god of thunder and lightning (Germanic Thor or Slavic Perun, although these names are not cognates of each other), a goddess of Dawn (Vedic Usas, Greek Eos, Latin Aurora), and a pair of divine twins (Castor and Pollux, Baltic Dieva Deli, Vedic Ashvins). He seems pretty confident that these figures can be reconstructed, and a lot less confident about names and details. Honestly most of the Pantheon section of the Wikipedia page you linked seems to follow Fortson pretty well, although it's written worse and doesn't adequately convey how speculative this is. This is a pretty recent work (not bleeding edge, obviously, but only a decade old), and so are some of the other works listed on the Wikipedia page, although I'm not familiar with the other recent sources.
I mean, it's a theory that is supported by the thinnest strands of similarities between stories told by Indo-European language groups. Not every group has the same stories, but there are similar enough stories to postulate that they might share a common pantheon. But the biggest issue is that the historical record ends far before most of these stories were written down. Again, the PIE Pantheon is a theory at best, but a damn interesting one.