Is my samsung galaxy s3 rooted

got a second hand s3 , when I try to update to jellybean from 4.0.4 it find the update and downloads it and then when I try to update it the cwm recovery menu appears. why is this? what does it mean? and I have checked on titanium backup and root checker and they say my phone has not got root access.

also

I have cwm recovery but I dont have superuser and on titanium backup and root checker it says I dont have root access. But I still have cwm menu why is this? and how do I get rid of it