We do sprints, which come from Scrum. And Scrum has artifacts. There are 3 official artifacts, the product backlog, the sprint backlog, and the "Potentially Releasable Product Increment". That's it. The only 3 artifacts of Scrum. Not tasks. Not acceptance criteria. Not burndown charts. Not velocity.
However, there are lots of things that get created when you implement Scrum (or scrum-like development). Such as tasks. And boards of tasks. And Acceptance Criteria. All critical things if you want to make it work. And what is that "Potentially Releasable Product Increment" thing anyway? What is it for, and what do you do with it if it's only a potential.
That increment is why we're here. It's the customer value we're supposed to be providing. One of the goals of agile development in general, including Scrum, is to increase the velocity at which value is added, so that total value over time is maximized. And that increment is the embodiment of the value.
Which means that the product increment is really the focus. It's the thing you want to get done. It's the thing that ties all the items on the sprint backlog together as a goal. You might have more than one if you have multiple things you want to improve at once. It might be that you can add more value by improving in 3 areas at the same time than by doing more in any one area. But either way, your sprint goals tie things together.
So stop thinking about your backlog as a series of unrelated tasks and start thinking about how those tasks represent a smaller set of goals that provide customer value.