It's probably an 80:20 problem of sorts. More like a 99:1. Externally, people mostly appear to be comprised of flesh and hair. Pick any random square inch and the odds are that you will land on flesh or hair. That gets different on eyeballs, but they are still just bags of goo connected to muscle. The devil there is in the details of the blood vessels and the iris and things.

And then you get to teeth, which are like wet rocks. You're building this thing that is going to bomb if it can't do soft, meaty, hairy things convincingly and then there's this itty bitty section you're only going to see sometimes that is a dark membraneous cave full of wet rocks.