I'm planning a book series called The Weasel Sagas. Things have been going great up until now, where I've realized I've hit a bit of a problem: I've come up with backstories for so many different characters all over the hero-villain spectrum that it would take 50 books to have time for all of the characters' motivations, backstories, character development, and arc resolution along with the plot and huge mass of worldbuilding. I've only planned 28 books for the entire series, and I don't think I'd live long enough to write 50 books. How would you suggest I tackle all of these characters while keeping the number books at 28 and needing as little simplification as possible to keep the story compelling?
Just so you can understand the sheer scale of this project, here are the three groups of MAIN characters:
Heroes (Knights of the Square Table): https://sites.google.com/site/weaselworldofficialsite/characters/the-knights-of-the-square-table
Villains (The Cabal): https://sites.google.com/site/weaselworldofficialsite/characters/the-cabal
Supernatural Characters (Deities, Spirits, Etc.): https://sites.google.com/site/weaselworldofficialsite/system/app/pages/subPages?path=/the-metaphysical