Being humble is not a bad trait to have, unless you're too humble and it's starting to affect your career. One of the biggest issues, as The Muse noted, with being humble at work is it can make you invisible. It's easy for others to overlook you and for you to not get credit where credit is due.
This is where your superhero skills come in. These are the unique set of skills that only you have and make you so great at your job. These are skills that have come naturally to you, but you've taken the time to hone and perfect, becoming better at them each day.
To ensure you don't become invisible at work, make your superhero skills known so that others recognize where you are needed. Also look for opportunities in which you can show off and put these skills to work. Make it so that you are the go-to person when these specific skill sets are needed.
This way, even if you are humble you aren't being overlooked for your work, and your superhero skills will speak for themselves.