Over the past weekend one of my friends was coming off a bit of a rough week and was more tired than normal for the Friday D&D game I run, and the Sunday Star Wars game we're both in. The result was he ended up being more quippy than normal. He was in that state of tired where his filter was off, and so he responded - in character - to more things than he normally did.
Which was completely awesome.
I like playing with this guy, but at times his characters can feel weird or flat partly because he can be so reluctant to speak up. But with the zingers and responses, not only did we get to see more of the character and get insight, but it prompted other people to speak up more as well. The game became more enjoyable, a couple laughs broke out out of character from snarky comments, and in general it made for a pleasant experience.
Now, I'll never tell you to do something you're completely uncomfortable with, but the thing I took from this - and I hope the friend did too - is that you shouldn't be afraid to speak up and give voice to your character. RPGs are as external for others as they can be internal for you, and if you don't interact at the table, let your character speak, or go and perform actions there is nothing there for the other people at the table to see or latch onto for your character.
This doesn't mean there is anything wrong with staying quiet if you prefer that. However, in general I would recommend making the effort to speak up and put your character into the game. Have fun. Triumph. Fail. Learn. Make things interesting. You can't do any of that unless you first speak up and have your character do something.
And for the rest, I know this seems super basic, but even DMing for 20+ years and playing for longer I am often the person at the table being quiet and letting everyone else play while I don't voice my character. The basic things need to be said sometimes. If only to remind us of how they work.
It's a game. Have fun. Play. Leave it all on the table so you can come back and pick up the pieces next time.