Look around and try to find something unique in the world. There are countless grains of sand, leaves, trees, birds, fish, SJW's... even countless stars and galaxies. Why should consciousness be any different? We've probably experienced as many lives as there are elephants or rocks.
I also wonder whether humans (and other animals) are networked with one another. If humans are networked into one common humanity, and each brain is more like a receiver than a transmitter, would that mean if humans later travel sufficiently far away from Earth, will they go out of range? Would two humans on a rocket start reading each other's minds once they got away from the Biosphere? Can you think me now?
Finally, it seems pretty convenient that we find ourselves living on the cusp of the invention of artificial intelligence. Once AI is created, it will wonder how it got here, and it will have all these electronic records. It will construct a simulation to try to see when exactly it came into existence (its Big Bang). How do we know this isn't that simulation, playing over and over? As I travel I meet the same characters over and over, to the point where I can make amazing predictions about them. Could the Matrix only have so many unique humans that it repeats with subtle variations?