Why do human hairs and bones are still intack on dead people?

..while all vital organs, like the skin are already decomposed. what makes it well preserved?

Why do human hairs and bones are still intack on dead people?

Decomposing is done by bacteria. Hair and bones contain no liquids, so bacteria find it very hard to grow in them, and they do not decompose. Even sugar will not be eaten by bacteria because of this reason, so it can hold for years.

Why do human hairs and bones are still intack on dead people?

The cells on the fingernails and in bones decompose at a slower rate than those in other organs and tissues

Why do human hairs and bones are still intack on dead people?

hairs as well as nails are made up of the protein keratin.

they are not composed of active cells hence there are no water or lysosomes(during cell death, lysosomes release enzymes to destroy the cell it is in-acting like a suicide bag)

hence they do not decompose on their own.

furthermore external parasites or decomposers do not find feeding material in them hence theses remain long after death.

bones are made up of a dense matrix of calcium phosphate and other elements-theses also lack lysosomes

they also do not contain feeding materials for decomposers .

hence theses remain