“How would someone who thinks this world does not exist account for their experiences in this world?”
You would be surprised to hear that people have all sorts of weird views. In the Brahmajala Sutta, Buddha listed 62 types of wrong views.
– There are many people even today, who believe that the world around them is all made up by the mind, for example. You can Google “solipsism” and read about it.
“By a father and mother being special persons, I think it means that we are deeply indebted to our parents for giving us the chance to have a human jati. Is this view correct?”
Yes. That is correct. Even if one is in human bhava, it is not easy to born with a human body. There are an unbelievable number of human gandhabbas waiting for a mother’s womb.
– For example, in rebirth accounts, there is always a gap of many years in between two adjacent human births.