There are many lessons we can learn from this. We can learn that even when life completely falls apart, even if we feel that we have been damaged beyond repair, there will always be a way to pick up the pieces. As President Uchtdorf said:
[I]f man can take the ruins, rubble, and remains of a broken city and rebuild an awe-inspiring structure that rises toward the heavens, how much more capable is our Almighty Father to restore His children who have fallen, struggled, or become lost?However, there may still be scars. We can to this world to gain experience, and not all of those experiences will be pleasant. We sometimes wish that we could forget such experiences, or that they never happened, but that would partially defeat the purpose of life. He need to keep the memories of those experiences and learn from them in order for them to help us grow. When they rebuilt the Cathedral, it was important that they kept the charred bricks as a memento.
Yet, we should remember that not everything can be reused. When life breaks us apart, that is sometimes because God wants to build us back up into something better, and not all of the bricks that make up our current selves have a permanent place in God's eternal plans. We each have some traits that we could do without, some habits that we should abandon, some vices that we should strive to overcome. We each have flaws that God would like to help us remove, and sometimes, that requires a complete remodelling, and while many of our bricks have eternal value and can be reused, many more of our bricks will need to be replaced.
Ultimately, God wants all of us to become like perfect Cathedrals, but "perfect" doesn't always mean "pristine" or "undamaged." Often, we go through unpleasant experiences, and we need God's help to build us back up. Thankfully, when God restores us, He helps us become our perfect selves, using only the parts of ourselves that make us better. When we fall apart, God puts us back together, and He builds us up even better than we were before, perhaps with a few pockmarks, but stronger and wiser for the experience. So, the next time things go badly, trust in God's ability to set things right, and trust in His wisdom to keep and reuse all and only the best parts.