How they contribute to solving the troubles that plague humanity is done at a personal level, one a person at a time so to speak. Let me explain. In my Spanish cong there are several examples of individuals whose lives we lived while drinking in excess, smoking, drugs, and other unwise ways; since becoming JWs, these same people seem to live a better quality, cleaner life. So, rather than distributing food at the KH, the teachings dispensed there are spiritual food that, when put into practice, help the subject to take ownership of behavior and adjust it for a better outcome.
SL
While working on Kingdom Halls we have many people show up and ask if we had a "Mercy or Food Aid" to help the poor. A station-wagon with three crying hungry babies and two tweaked parents, not the first time and not the last. Piously we showed them our building and handed them a few donuts and snacks the congregation brought to help the workers. They were not really impressed and neither was I, I have seen from decades of being a elder and longer being a JW, we don't help like you claim. Maybe it's because I've been in the Mandarin, Spanish, Aremenian, Tagalogog, Hindi, French, English, and Japanese groups, perhaps I was too busy helping form these new language groups while attending two sets of meetings to see how we help them.
The first time I attended a local church (Non JW) that was deeply invovled in the community, I was shocked at how calloused our religion is. Than researching the Early Christian Church and how people benefited greatly by knowing a group that opened up it's arms to all instead of focusing on itself, that's when I realized JWs are not Christian, they are a offshoot of a White Adventist Religious Movement with no ties to anyone outside their congregation(as if being in a congregation is a guarentee the JWs will help their own. Many here have proof that JWs don't give shit about their own, so why would they care about the World and it's Poor?). This is just the ramblings of a Elder who is burned out after helping brothers start many language groups, often the new language people after learning English bailed on us because we offered them nothing of value, we don't preach Grace and boy do we judge each other's works harshly!