Answer:
When the author says that our identities come together to “make us a house of flamethrowers/.”, I think he meant that humans are different and because of that difference there will always be conflict.
I think it also has something to do with instability because a flamethrower is erratic and not stable.
When the author said, "a river of living things", I think he was referring to how different people are and how our identities intersect.
A river can be a home to many different sea animals and no two sea animals are the same.
I think it can also mean that despite the differences, we still find a way to co-exist and move together as a society just like the river.