Keep in mind that this common ancestor most likely didn't walk on two legs, wasn't hairless, and probably couldn't control its breathing, making it impossible to either talk or swim. So, yes, chimps certainly must have evolved somewhat, but not as much as humans and not in anything resembling the same direction. Therefore, this common ancestor was an ape (not a "monkey" as some insist on suggesting), though not a "modern" ape.
Also, no one seems to have pointed out, this creature bears a strong resemblance to modern yeti/sasquatch/bigfoot sightings.