To me, it's all about good time, staying in the pocket and melody. knowing how to write songs is way up there too.
IMO, you don't need to be Wooten or Jaco or know how to slap like Flea to be a good bassist.
We all bring something different to the table whether that’s technique, songwriting style, tone or dexterity. It took me years to realize that it wasn’t all about how fast you could slap or pop or how many different scales you could play. Those things help for sure. But they aren’t NEEDED to be a good bassist/musician. As long as you have the drive, good timing, can play in key and get along with others, you can be a great bassist. I look at some of the “greats”, the guys who are remembered, and a lot of them didn’t know scales or chord progressions, some didn’t even know an E from an A. They may have learned those things over time but it’s not what made them great. See, to me, what sets everyone apart, tone and song writing. You could be a mediocre player and get largely recognized and praised. I guess my point is, you don’t have to be Marcus or Stanley to be “great”. You just need the passion, drive an confidence. Timing is a must at some point but these are things that come after you’ve made a decision to throw yourself into the bassists role.