They are neither from earth or space, but another dimension. Also, they are NOT offspring of Nephilim, Nephilim are the offspring of them.
Christians tend to “spiritualize” everything, including this “spiritual warfare”, some popular teachings point fingers at your shame, guilt and fear, while the real enemies, the principalities are working around the clock through personalities to kill, steal and destroy. So yes, there is more, but how about we deal with what I’d described first? ‘Cause it’s shove up in our faces, and the bridge is burned, there’s no place to retreat.