I'm only halfway through it myself. While likewise overwhelmed, it is apparent that we have been judging his work as mythology, which, by his definition, it is not. He's making a very academic argument for the definitions of a "Fairy story" which may be what we now call fantasy, but I think he'd refute that, pipe in hand, tweed jacket and all, and cut my presentation to pieces.

He talks about the realness of the created world. It must be believable - not a dream.

I think Tolkien's scholarship is what sets his works apart from his imitators. He knew this genre backwards. and way back at that. He said that creativity was the mold on a compost pile. All that you learn is the detritus that builds the pile. The mold is something new.