what's the meaning of "occupying one's skin"?

The excerpt is from the following lines:

Mules and other brutes had occupied their skins. But now, the sun and
the bossman were gone, so the skins felt powerful and human. They
became lords of sounds and lesser things. They passed nations through
their mouths. They sat in judgment.

• Source: Their eyes were watching god, by Zora Neal Hurston

thanks in advance