The bad thing I guess would be the first impression I am leaving, I am working on changing this.
As for the rest you mentioned, I don't think it is a problem. Specially if it does you no harm at your workplace But I do very much prefer being friendly with all people and being able to break the ice with anyone.
I got introduced to a person lately who instantly talks with stranger and drop jokes.
Sounds like your just naturally a shy person. I can relate. Growing up I was very shy and slow to talk to new people. Getting up the nerve to ask a girl on a date was torture. Working in the public forced me out of my comfort zone. I'm still shy but talking with others comes easy now...and I have a beautiful wife, so that worked out too. I wouldn't worry too much about it. Just smile and introduce yourself. It really is that easy. The more you do it the easier it becomes.