Universal Merlin

What if Merlin lived in a world where he lived as a ghost in the background?

Or

What if Merlin actually was from an alternate dimension, which was similar but still different from the Camelot that we know? He lived out his life and was reborn in our dimension, and became what we know him as with all the knowledge from his old life.

Or

What if Merlin was once a young boy who lived to read about the knights of the round table? One day with his trusty boom he entered into his grandfather's library in the attic, and an accident was put in charge of managing the dimensions just like his grandfather.

Or

What if it was all of these and more as Merlin lives multiple lives across time?