Generally, serifs have a longer history than san serifs, as they were the first typefaces used to print the novels following the invention of the Gutenberg Press.
A Typeface Overview For Print And Web Design
Nick Babich
1999

Except… well… no they weren’t. The Gutenberg Press used a blackletter face based on calligraphic handwriting. And they likely weren’t printing any novels… not enough people could read to make a serious go at printing novels (which nobody was even writing for the first hundred years after the invention of movable type).