No matter how powerful a living being might be, the most important thing that they required more than anything else would be the vital air, oxygen, without which it would only take a few minutes for the soul to perish and then become nothing but dirt.

It was said that God made the first human from dirt, and then God breathed air into their nostrils to make them a living soul. So, it was only fitting for the humans to return to dirt after death.

Now, human blood had life in it and would mix well