I honestly don't see any possibility of truly "wide-spread benefits for humanity" if AGI is achieved anytime soon. Current state of humanity when it comes to how we treat each other and anything akin to species-level awareness and collaboration is only barely better in recent history than the dark ages. If a group of people gets access to an AGI, I think it will very quickly result in a bit wider group than that having their lives prolonged, no disease, no lack of resources and practically infinite wealth, and everyone eventually being either rid off, or allowed to live in far-away slums and left to die off.