You could go to his
wikipedia page where it says "Greenwood grew up in the upscale
Toronto suburb of
Don Mills. He began writing stories about the
Forgotten Realms as a child, starting in the mid-1960s;
they were his "dream space for swords and sorcery stories". Greenwood conceived of the Forgotten Realms as one world in a "multiverse" of parallel worlds which includes the Earth. He imagined such worlds as being the source of humanity's myths and legends."
It cites the book
30 Years of Adventure: A Celebration of Dungeons & Dragons.
I think the first realms story in Dragon (edit, it was not Dragon, it was a pre-Dragon story) was a Conan type character who goes after a villain in a tavern, but the villain is actually a well-known powerful magical villain well beyond an ultracompetent well-thewed barbarian's ability and he knows it, but as the death magic begins, two other customers drop their magical disguises and the Symbul and Elminster blast the villain. They then exasperatedly explain how this ruins their undercover operation to learn about villainy going on beyond the one they blasted. So it starts out looking like a Conan type story in a sword and sorcery world, then does reveals about powerful magic users that take over the narrative from the protagonist and subvert the tone with the always a bigger fish trope.
Apparently also Elminster was supposed to be an only occasionally showing up quirky Tom Bombadil archmage who could save people and occasionally help out but end up being so quirky that he would not be helpful if relied upon too much by PC types and it was supposed to focus on PC type protagonist heroes, but he kept being asked by TSR to write more Elminster stuff including him as a main character in books and stories and Sage narrator overview of sourcebooks so it just built and built.
Thay always struck me since 1e as a D&D version of Conan Stygia/Acheron with fantasy evil Stygian sorcerers as exotic pulp bad guys. Both are fantasy Egypt stuff with fantasy big magic users in their setting, but the Realms are a bit higher magic.