I find it difficult to believe that a person could live to be that large.

The upper limit is slightly over 9 feet tall. Bone densities and proportions would result in no one recognizing a femur (or any other bone) from a humanoid giant as compared to some other beast.

Its a matter of proportion. While the height increases slowly, mass of the body would increase fast against height. Thus a person 9 foot tall would have a mass greater than a person at 6 feet tall even of the same proportions.

Further, blood flow is such that human skin and blood vessels cannot contain the blood at the feet. Robert Wadlow, the tallest man ever recorded, stood at 8 feet 11.1 inches tall. He died due to breaking blood vessels in the feet and lower legs which became infected (blood poisoning).

The greater volume of blood means greater mass, which means that the pressure in the lower extremities is far greater than the blood vessels can withstand.

The Heart alone would have to grow to far greater proportion to handle the extra amounts of blood. No human chest in proportion at a height greater than nearly 10 feet could contain the heart that would be needed to move the blood around.

Medically speaking, its impossible for a person to get much over 9 feet tall without serious systemic failures across every bodily system.

Either the height estimate is off by about 2 feet, or this is some other creature (not human) thus not technically a 'giant'.

It is highly possible that it is of one of the hominid lines which died out, thus an 'apeman' sort of creature that attained a large size.

A Gorilla spine, or some arm bones, or the shoulder or the pelvis could readily be mistaken as 'human' and the height estimate one would get would be far greater than the height of a gorilla, simply due to the the fact that gorillas as massive above the waist, and 'small' below the waist in comparison.