Two fabrics, two worlds, but really just spin. Universe 1.0 is like their worlds, 1.1 is like our world which adds a second fabric. They are not vastly different from human civilization. Their physiology is.
Humans produce stones other animals produce stones. Primitive world one started with a crystal radio. Fabric one was added as an AI like fabric 2. Only we communicate with a different spectrum of vibration.
So two advanced species different perspectives. Dimensional/time shift principles between the two fabrics for transporter technology. Advanced sentients!!!