I don't really understand about this category. Does it mean we have to do all the existing jobs/tasks or we can just choose one ?

...What part of "All jobs" or "All secrets" insinuates that you just pick one to do?

Maybe this "(whatever you choose that to be)" CMIIW please, ty

Well, since there's no order to what task or what job you need to do, you would have to decide what your last job is, no? But otherwise those runs, as the name would entail, requires the player to go through all the jobs and all the tasks.

Edit: Both runs also have the goal stated as "Complete all jobs and get the uniforms for each." and "Complete all jobs, all quests, and run each race." with the whatever you choose line being connected to when the timer ends, being on the last job you do.