I've been wondering this for a while and haven't the slightest clue as to what the original summoned hero story is, I can look back decades before I was born and find stories that seem as though they are already employing the tropes and playing with the setting like its existed for a while. so what is the oldest version of this you can think of?
Dragon quest and Zero no Tsukaima Ps: if I not wrong also, Zero no Tsukaima also the first Light Novel been animated
Depending on what you consider a light novel, Legend of the Galactic Heroes is the earliest I know of.
Huh I've never considered that but it definitely hits the nail on the head especially when you think about the religious inspiration of it Does the divine comedy count?
Yes, Legend of the Galactic Heroes is supposed to be one of the first light novel adapted in anime form (and it's a masterpiece space opera from madhouse , so go watch it right now if you haven't yet !), as the novel was first published in november 1982 and the first movie was released in february 1988, and the long OAV run (110 episodes ) started in december 1988. Technically, Guin Saga is an older light novel (started in 1979, and it's still ongoing with 141 volumes as Kaoru Kurimoto, the original author who died from cancer in 2009, left a lot of unpublished content and even full plans for the future of the serie as she wished that her life's work didn't end with her death) but it was adapted way later in anime form (in 2009). Too bad nobody was gutsy enough to translate it, as there was a few official translations of the first arcs but it never went very far... if we go for isekai (transported in another world stuff), it's a pretty old trope for mangas as there was a previous isekai fad in shojo stories (but somehow mixed with time travel elements, many went also with the summoned saintess against an evil (but sexy because shojo) demon lord template) that started with Oke no Monsho (Crest of the Royal Family) in 1976 (by the way this manga is still ongoing with 66 volumes), the theme of this one is quite close to time travel but with a heavy fantasy in ancien Egypt style and was adapted in illustrated story video form also in 1988, close to a kamishibai style ported on screen (not an anime, more like drawings with very limited animation, voice overs and music, by no less than Joe hisaishi !). Fushigi Yugi (1992) and Kanata Kara (From far away, 1993) are good exemple of more recent successfull mangas following this long lasted trend (just as Inu Yasha was in 1996). Talking about old stuff that was animated, Ogon Bat (Golden Bat) may be the oldest well documented one as its first stories started around 1930 in kamishibai form and the anime started in 1966 (by the way it is also supposed to be one of the first modern super hero, way before superman). It also got the full package of adaptation with novels, mangas, live action series and all sort of merchandising suff (more than what you could ever imagine because Japan is Japan...).
Technically, Alice's Adventures in Wonderland (1865), the Wondefull Wizard of Oz (1900) and Peter Pan (The Little White Bird in 1902) are also isekai themed stories... Maybe Seisenshi Danbain (Aura Battler Dunbine), a february 1983 anime, might be one of the first big succes in the male hero transported in a medieval fantasy genre but it was heavily mecha themed... 異世界の勇士, Isekai no Yusha written by Haruka Takachiho that started in a magazine in 1976 and was first published in light novel form by Tsuru Shobo in 1979 and republished by Tokuma Shoten in 1981 may be one of the first story that had the full set of classical summoned hero in another world tropes but it's a very obscure work and I wasn't able to find much about it... Here is its cover, seems like it was heavily influenced by the style of the old american fantasy pulps :
There's also Magical Knight Rayearth. But yeah, it's pretty clear that the biggest influence on modern isekai stories is Dragon Quest. They even tend to have horned bunnies and slimes for newbie adventurers to hunt. I'd also say that the original Ultima games has the same hero summoning template that is common to modern isekai. Now I don't think that the writers of these books are familiar with the Ultima games, but they were a huge influence on the original JRPGs like Dragon Quest.
What came first Narnia or alice in wonderland? Would alice even count? Was the queen of hearts the maou?
Alice came first, and it's transported to another world, and the reason for Narnia being a summoned hero is due to the kids being prophesied and called to Narnia to save the Narnia.