Pre-Faerunian Pantheons

==== The faerunian pantheon was made of five or more pantheons that merged, including the Netherese pantheon, Talfiric pantheon, Jhaamdathan pantheon, Coram****e pantheon, as well as others like the Untheric pantheon. What other pantheons merged into the faerunian one, and are there some detailed lists of the deities of each? ====

We don't have a fully comprehensive list, or even decent lists, of the fragmentary pantheons of Faerun. I would expect that in addition to those listed, the unidentified others referred to are meant to indicate the interloper deities who have become key elements of the Faerunian pantheon. Fans at Candlekeep have been working on sorting these out, of course, and some fairly good ideas on the matter can be fou

==== So there are various implied connections between D&D settings and Earth. Is it implied that various Pantheons with real-world analogues (Finnish/Egyptian/Greek/etc.) got their start on Earth, or did they likely have their own worlds on the prime distinct from our own? ====

We know that the Pharaonic pantheon were worshiped on Earth at some point, but given their nature and power and the nature and lack of power of the world of Earth, it's likely that each of the major pantheons had their own home sphere and world. I've done some tentative sketch-ups of those worlds, but not much.