No, all number lines do not need to start at or include 0. Some sets of data cover a range that includes very large or very small numbers. It would not make sense to create a number line large enough to include the range of data and all of the values all the way to 0.

For example, if you need to plot 357, 355, 362, and 364 on a number line. You would not want to create a number line that starts at 0. Your number line would be very large, and your data would be very squished in order to make it fit. 

When creating a number line, choose a range that includes all of your data points but does become over complicated.