Indeed it doesn't mean that, you are right. We share so many genes, so loosely speaking, we are their descendants. Which we are not, but for all practical purposes, we can approximately find correlations between our species, and that one, better than any other.
We are descended from chimps in the same way that I am descended from my cousin.
Edit: I'm realizing this could be a language barrier. "Descendent" is the inverse of "ancestor". A descendent is directly downward in lineage from an ancestor.
Oh, yeah, maybe that is. So with chimps we share a common ancestor. Even more accurate, chimps are our closest relative species living on earth today, with which we share the more close/recent ancestor.