Can someone explain this Jewish joke?

Question

I'm not Jewish so perhaps that's a pre-requisite for understanding this joke but I'm still interested to know what's so funny. Can someone please explain?

There is a Jewish story, an ordinary Jewish joke: A father was teaching his little son to be less afraid, to have more courage by having him jump down the stairs. He put his son on the second stair and said 'jump, and I'll catch you' then on the third stair and said 'jump, and I'll catch you', the little boy was afraid, but he trusted his father and did what he was told and jumped into his arms. The father put him on the next step and then the next, each time telling him 'jump, and I'll catch you'. Then the boy jumped from a very high step, but this time the father stepped back and the boy fell flat on his face. He picked himself up, bleeding and crying, and the father said to him, 'that'll teach you.'"

Answer 1

Father is teaching his son not to trust or rely on anybody.

Perhaps useful for those of the Judaic persuation.

Answer 2

actually it doesn't seems not like a joke to me

Answer 3

Yeah, it means don't rely on anyone, not even your family!