If you were to meet a humble person, he wouldn't be the kind of person who thinks lower of himself than others think he should. Instead, he would not think of himself at all! A humble person isn't interested in saying "I suck" or "I'm not that great". These statements come from a person who thinks he should be better than he is. A truly humble person isn't concerned with who he is or who he should be. He isn't concerned with himself at all, but instead he's concerned with other people.
She's so humble, I don't believe she thinks of herself at all!