If you've ever strolled into a room in the house but then can't recall what reason you went in there for in the first place then you'll have some empathy with good old Marilyn Manson. I've drawn it for you. You're welcome.
Wikipedia used to list 34 subgenres of heavy metal. These included everything from Christian Metal to Neo-Classical Metal - I'm particularly intrigued by Nintendocore and Viking Metal - so this is indeed a rich and diverse underworld of music that most of us have not been exposed to.