The problem I have with the question is that it implies sapience and will. Because that's where "purpose" comes from. I don't see any reason to ascribe those human characteristics to God. I see God as more like gravity than a superman. Gravity doesn't "decide" to make rain fall or ignite nuclear fusion in a star. It just does.Why did god create humans?
I like to think that humans, and living things in general, have a tiny bit of God in them. But God doesn't decide to make us individually, it's more like we are drops of spray flipped off the top of an ocean wave. We exist separately for a flicker, then fall back in. When that happens, the drop doesn't cease to exist. It merges back into the ocean it came from. Similarly, when we die the important part of us merges back into God. Like the droplets of spray. All that disappears when we die is the illusion that we are separate from God.
Tom