What if this is the afterlife to a life we lived before this one?

@SW-User basically.

And if it's true then that would mean life is fair and that bad things only happen to people who at least use to be bad.

I don't think that it is true, mind you, but it's an interesting thought.

@Eternity I don't see Karma as a punishment. I see it as a consequence of our choices. It is not that bad things happen to bad people. Bad things also happen to good people and vice versa. Somewhere between the past lives and Karma, I also believe there is a soul contract learning - we choose what we want to learn and some experiences are necessary to get us there. And some consequences of our acts in the past need learning too.
At the end of the day the whole journey is about the dissolution of the ego. In the most rudimentary and simple terms - but there are so many layers to this.