holy crap you guys really deviated from the topic. arguing about what you each consider to be a BB is a bit useless. since its your own thoughts, no one person can say either of you are wrong or right.
i achieved my junior BB (junior shodan-ho) when i was 13 going on 14. i was then promoted to junior shodan, then full shodan when i turned 16 (which is the difference between juniors BB and B

. i saw people younger than 10 earn their junior shodan-hos in my style, and although they are allowed to judeg in tournaments and teach the class, they only teach during the warmup/workout half and help the main isntructor during the second half (where we do kata, sparring, blocks and counters, drills, etc.).
these juniour BBs are treated as BBs in our style, but my shihan treats them according to their age AND rank. we had some younger BBs who were very knowledgable and talented, and thus were treated as older BBs, and we also had those who just met the requirements and attained their BB, and were treated and given responsibility according to their skill.
in my style, anyone can earn a BB so long as they meet the requirements. that being said, you are given responsibilty according to how seriously you train, hold your rank and good you are. although having a BB is an achievement, i do not see it as grounds for thinking someone is good in my art, rather they met the requirements. i see you as talented when i see you display and teach your understanding and knowledge of the art.
i am still just a shodan (i am in the limbo area of going for my nidan, though i was notified of my grading back in dec 06, i never completed all the requirements therefore i was never promoted) however i know that my understanding of the art, my abilities and my teaching is superior to some of those who are higher ranked than i am. the only difference is they completed their requirements (teaching time, essay, filming). despite this, my shihan treats me like a higher ranked student because of my skills, which i believe is how it should be.
a rank shows commitment, dedication, and filling the requirements (which differ from school to school). however, it is my personal belief that the rank is only part of how a student should be regarded. yes, a person with a higher rank may know "more" in terms of katas or what not, but they may just go through the motions, and not understand all there is to know about what they are doing. thus, ones own personal ability and knowledge should also be taken into account.
all that being said, i know with many schools, maturity and age play a part in rank, which is important. there are exceptions at times, but 5 is a bit too young. does this 5 yr old know the applications of these katas? does she know what she is doing and why she is doing them? can she teach these PROPERLY to new students? can she teach at all? many unanswered questions, though i will guess the correct response would be no for most of them.