I call Scenario #2 reflex. Most people call it reflex, or even learned instinct. What do you call it?
Maybe 'preparedness' in the technical sense, but not reflex. 'Ducking' is an escape reflex that only involves the brain after the fact, assuming survival.
Reflex (by definition) does not involve the brain. They synapse in the spine, in the case of a reflex like the withdrawal reflex, 'ducking', or in the muscle itself in the case of a reflex like the patellar reflex, 'knee jerk', with one chemical synapse from the sensory neuron directly to the associated motor neuron.
A polysynaptic reflex can be inhibited in the spinal cord, so you can make yourself be hit in the head by the ball.