This is a common reaction among foreign tourists who have read a lot of scary crime stories online. Once you get your feet on the ground, you have a more accurate feel for the realities of the situation.
HOWEVER, this does not mean you should not remain vigilant at all times !!!!!!!
Brazilians seem to have better built in radar, so it often does not outwardly show, but they also have a lifetime of knowing what to watch for and how to avoid incidents.
I often compare foreign tourists to Mr. Magoo of the old cartoons, the mostly blind character who luckily stumbles unhurt through dangers he is not even aware of.

Enjoy your Revellion !