Loneliness.
I can be man or animal. I can be a man or a woman. I don't have a heart so I can't be killed. Tickle my feet, I will not move. What am I?
I have one of the three numbers: 1, 2, or 3 in my mind. I speak only the truth. You can ask me just one question for which I will only reply in yes or no or don’t know. What question will you ask me so that you are able to know the number?