First off: I can't take credit for this thought. It is my sister's.

Basically it's this: Everyone sees you as something different, one person might think of you as shy whereas someone else may think of you as the craziest person they know. So you could be a thousand different things at once, because you're something completely different to each person who knows you. Therefore, how can you know what you actually are? Is there an absolute truth about yourself or is it all relative?
I guess all we can do is refer to the Bible to find the truth about what God says we are, as that's all we can know for sure. We know we are loved by Him, we are His children, we are made in His image, and so on and so forth. We can take comfort in the fact that we are special and unique to God.