I don't know about a study proving that, might be true. But from my own experience, toddlers are not afraid of anything until a. they hurt themselves, b. they develop more and understand the concepts like height, c. the parent repeats "no" to them and/or shows them what to do or not to do until they learn.
So there might be evolutionary pre-programming in the human brain, but toddlers brain still needs to develop until those became active. I think there should be more research into how toddlers learn to crawl, stand and walk, how they learn to speak, etc.
Not sure if you are a parent, but this isn't the case at all!
Not sure what to think about it.
I'd say this proves the point completely. It shows that babies aren't scared of heights, and they don't acquire the fear from experience. Instead it seems likely it is that they either develop a mental model of how the world works, or they learn from watching other's behavior.
If there is a cliff, toddlers are scared of being nearby. They definetely don't have the ability to "imagine=simulate" the consequences of falling over the cliff. The fear is in the structure of neurons of brain.
If you feed classifier algorithm with images of black dogs and white swans and then want to classify black swan. Both classifying it as dog(because of color) or swan(because of shape) are right. The difference is only in bias, which features do you prefer.