I was under the impression that all sins are rooted in shirk (either concealed shirk or manifest shirk). I also believed that most of us are mushrik based on this verse:
For example, a lot of us use Allah as a means and not as an end, we want to worship Allah so that we can go to heaven, this would be defined as concealed shirk, though it does not mean that we would necessarily be deprived of heaven for doing this. This is what I heard from Dr Farrokh Sekaleshfar here.
Simila