Upvote:2
You're not excluded from the Standard Visitor Visa even if you're a close relative of the person you're visiting.
This category is the one most people will use if they are not travelling to the UK for work/business or study. The use of "family" in the description is in my view, an attempt to make the text more understandable. It doesn't mean that you can only visit family. You can visit friends with whom you have no biological relationship, provided of course, you meet the relevant qualifications for the visa and are granted one.
I have had a few members of my extended family visit me using this route.