Is it possible that there are mistakes in those monsters? I’m not aware of an official errata, so if it exists, please point me to it!
– Ogre (damage should be d8+3, since it’s Large, not Huge.)
– Hill Giant (damage should be d8+5, since it’s Huge, not Large.)
– Ettin (should be Huge, not Large, since its description says it’s a Hill Giant with two heads; so damage should become d10+ 5 instead of d10+3, and HP should be 20 instead of 16.)
– Dragon (HP should be 20 since it’s Huge, not Large.)