If you feel humbled, you feel meek and modest, not important.
It is said by many people (but certainly not all) when they receive a prize or recognition.
You can also feel humbled if you suffer a great defeat by someone else.
The first way is positive, showing virtue. The second way is negative - at least you would look at it that way.
In the above sentence, the person is saying that they feel they feel very grateful and meek that such a number of people would appear to see him/her.