Let me prompt this by saying, by no means am I a scientist. My reply might sound like a blanket excuse, but this is what I've been told.
You have been brought here by a uncontrollable wormhole that was in Central City that was brought on by it being unstable. They tried to close it, but by mistake reversed it and cloned the wormhole instead, like how tornado can split apart. They are unaware on why it split and suddenly started to pull in random people from other times and space, but they are working on it.