Don’t be intimidated, be detailed.
These sheets can be annoying to some, but it’s an ingenious form of organization and a good tool to keep characters apart. This particular template is so detailed that it’s primary use is for main characters. For someone writing a series it might be wise to use the template in a more broader sense; characters like Neville Longbottom can always become important in later books! Remember, not everything needs to be filled in immediately, add more to your templates as your story develops. I personally look at mine for motivations, but all authors use it differently.