The most important scene in chapter 1 would have to be when Coyotito got bite by the scorpion. This scene was important because the news about the bite spread so fast and all of the neighbors came around because they cared so much for the sweet little baby. This scene showed Kino and Juana that even if you don't have a lot in your life, you still have people who care.
The most important scene in chapter 2 would have to be when Kino found the pearl. This scene was important because even though no one believed Kino would every find a pearl he never gave up. After finding this amazing pearl people from the town even started being nice to Kino just because of the money the pearl would give him.
Lastly, in chapter 3 the most important scene was when the doctor tried to steal the pearl from Kino by breaking into his house. Even though Kino couldn't see during this break in he still did everything he could to try and protect himself, the pearl, and his family. This is extremely important because it shows how much Kino cares about his most prized possession, but it also shows how money or fame can drastically change the way that people see you.