The world will not be destroyed by humans, but the world in which we know it will be, that I have no doubt. But i guess it's how you are defining world. World as in the Earth? Or as in one entire country? etc. Regardless what happens, humans will find a way to continue living, even if every nuke went off right now. The only thing we won't survive is the sun expanding. But hopefully we will have left Earth by then. But that's somewhat off topic.
I do not believe everything was created by a higher power. Im on the fence of all the materials for the universe as we know it being created by a higher power and then everything falling into place over such a long time. The reason why i think this is because, although not all, but a lot of what we have studied over the years, we have figured out, understand, or came up with very probably theories.
But whether or not a higher power is the cause for everything, Scientist have figured out how a whole lot of things work, which shows to me that a higher power is not needed. All that is needed is the right ingredients and enough time.