James Jamerson was a perfect storm.
He had a total understanding of musical theory, perfect timing, unique harmonic ideas, an ability to think and play on his feet, an understanding of how the bass could enhance and lead a tune, how to play complicated and busy lines in a way that didn't detract from the song, a bunch of fellow musicians, producers and writers who happily gave him all the space he needed and a record company boss who allowed him to do what he liked and paid him a fortune at the same time, all driven by an ego the size of Texas.
He developed a totally new and unique style of playing. After JJ the role of a bass playing got significantly more complicated!