There is another interpretation for that. Future humans built the tesseract... but no one knows from which universe. The tesseract is supposed to be something t

There is another interpretation for that. Future humans built the tesseract... but no one knows from which universe. The tesseract is supposed to be something trans-dimensional, maybe trans-universe. So it could be future humans from another Earth seeing this one dying, and doing something about it. If an entity from "outside" built the (first?) wormhole and created that closed loop, there's no paradox.