What really was the first book?
Storytelling goes beyond recorded time. Archaeologists would like us to think that handprints on a cave wall, swirls, and animal figures are religious and mystical, which they might be. But, in truth, they are stories, told over and over by the fire, lulling children to sleep. We just don't know how to read them.
Our alphabet would be just as foreign to them as their handprints are to us.
"Some say the first series (and book) (ie written down) was the Epic of Gilgamesh, an account of the historical figure Gilgamesh, who ruled the Sumerian city-state of Uruk, sometime between 2900-2300 BC."
Others say the first (pubished) series was in the 18th century series. The Poets of Great Britain Complete from Chaucer to Churchill, by British publisher John Belle in 1777. https://en.wikipedia.org/wiki/Book_series, Wikipedia > Book Series
"I just wanna read a good story that hasn't been altered to sell more books."
Okay, that might be unfair, or is it? Several popular series, seem as if someone stopped mid -story, drew a line and said "make this the next book." Unfortunately, to the detriment of good story telling.
Some series are started by an author with the whole series already in mind. Other series happen after a book is finished and the author chooses to continue the story, either with the complete stories of the other character or continuing where the previous books left off.
On my own list of series I gladly read include:
The Harry Potter books, by J.K. Rowling who have the distinction of being the highest selling series of novels with at least 500 million copies sold.
The books that spun off from the universe of Ender’s Game by Orson Scott Card.
The Outlander series by Diana Gabaldon, as of this writing 9 books, a 10th planned and a plethora of side stories of the characters, each of which could spin up a series of their own.