The creature you're describing could be a species of primate, specifically a small-bodied hominin like Australopithecus. These early ancestors of modern humans had a relatively small brain cavity compared to modern humans but exhibited a jaw structure and teeth that were more similar to ours, indicating a diet that likely included both plant and animal matter. This combination reflects an evolutionary adaptation towards bipedalism and complex social behaviors.
Australopithecus
You have normal cavities in your body: chest cavity, pelvic cavity, brain cavity. If you mean teeth, those are caused by disease.
The teeth are located in the oral cavity ( the Latin terminology is stomodeum).
faster transmission of nutrients thoughout the body
The oral cavity is located in the head and neck region of the human body. It is the space inside the mouth where food is ingested and begins the process of digestion. The oral cavity includes structures such as the lips, tongue, teeth, and salivary glands.
The oral cavity
The "Wisdom teeth" are technically called the 3rd molars.
The lips, the tongue, the teeth, the gums, the lining inside the lips and cheeks, the floor of the mouth (under the tongue), the roof of the mouth and the small area behind the wisdom teeth.
the enamel or the cavity
The teeth form the boundary between the buccal and lingual cavities.
By the cavity size inside the skull based off a human skull cavity size today. Different material wears down the teeth at different rates. So depending on where the body was found and what plant matter grew there or animals grazed there would determine the food sources.
The teeth would be considered "odd one out", because it is the only part of the digestive system listed that is an ACCESSORY structure.