JoJo's Bizarre Adventure follows a family bloodline and what happens to people within that bloodline.
The manga started in the mid 80's. The manga as a series is separated by acts or arcs, with each act or arc having a new protagonist that's part of the Joestar family tree. Each arc has its own protagonist with characters returning as side characters often. Time flows forward, time will jump ahead.
So far there have been eight arcs.
In the 90's, there were OVA's for the third act, Stardust Crusaders. This wasn't a 1:1 adaptation though, there were differences in story and characterization versus the manga.
A few years ago, the adaptation for the first act was made. The first act is called Phantom Blood. From there, two other acts have been adapted, and now we're on the fourth act for the anime. The anime is a 1:1 adaptation of the manga.
So, JoJo in animated form adapted straight from the first act of the manga, started a couple years ago. The fourth act is getting adapted now as well.