Do you have any basis for such a guess? During mating contests, animals aren't afraid of pain. When a carnivore grabs its leggy prey by the buttocks, it gets kicked and often has broken bones; yet the carnivore continues hunting, because it needs food in order to remain alive. I recall an episode of Planet Earth from two weeks ago where a wild dog was chasing an antelope (or what was it?) and the prey jumped into a pool of water even though it wasn't a great swimmer and couldn't stay in the water for too long (thus, gave in to prolonged discomfort in order to avoid death). Humans fear pain because this fear is necessary for our survival. It's not an invention but an instinct that we're born with.
I think avoidance of pain is not necessarily the same thing as fear of pain.
It may seem a pedantic point to make, but I think it's an important distinction to recognize.
I know that if I place my hand on the hot frying pan, it will hurt a great deal.
By not placing my hand on the frying pan, does that necessarily imply that I fear the frying pan, heat or pain?
I don’t think it does.
If I were afraid of frying pans, I would never touch one again.
If I were afraid of hot frying pans, I would never cook again.
If I were afraid of pain, I would also never cook again (or do anything that might result in hurting me).
When I cook, I do so taking care to avoid touching the hot surfaces, because pain is unpleasant.
What suggests to you that it is any more than simple avoidance of that which causes the discomfort of pain?
This is not to say that there is no such thing as survival instinct.
Instinct, by definition, is not rationalized, however.
Look at your antelope.
He went into the water because he was trying to avoid the pain of being attacked by a vicious dog and he was trying to avoid death.
Avoiding death is simple survival instinct – it does not imply a fear of death.
Why do you think animals don't fear death?
As I said, I think they lack the ability for complex abstract thought and belief systems to even grasp the concept of death, let alone fear it.
Fear of death requires the ability to consider and conjure complex abstract ideas.
You must be able to grasp the concept of death and consider the outcome of your death to harbor a fear of it.
Animals, by all appearances, do not have this ability.
As much as it may upset some atheists to consider, one of the most significant aspects that separate humans from the rest of the animals is religion.
Religion, Worship, Philosophy, Ethics – these are all complex, abstract notions that animals show no ability to grasp.
Yes, I know that some animals appear to have complex social rules and practices – that is a far cry, however, from the practice of exploration of ethics and justification of actions.
Fear, is an abstraction.