VNs are not games. They're a kind of ebook.

But only people who are really into computers read them, so they like to use game terminology to talk about them.

(also, none of the creators of "VNs" call them "VNs".)

Some VNs have no real choices and could hardly be called games. Others are deeply branched.

By the 2010s many JRPGs such as the Hyperdimension Neptunia series and Danganronpa pretty much stole all the visual elements of visual novels and mashed them up with gameplay from other genres.

By now the term "visual novel" got re-imported back into Japan so even Japanese creators have started using it for what they otherwise call "novel games" and VN-like "adventure games".