The Best of Shaggy was created on 2008-08-04.
The Boogeyman was created in 1978.
The Shaggy Man of Oz was created in 1949.
The Return of the Shaggy Dog was created in 1987.
The Shaggy D.A. was created on 1976-12-17.
Angel - Shaggy song - was created on 2001-05-28.
Shaggy
Hanna Barbera created the show Scooby-Doo and Matthew Lillard is the voice of Shaggy so Hanna Barbera created the show and Matthew Lillard did the voice of Shaggy. If there was no Matthew Lillard and no one else did Shaggy then Shaggy would not be in Scooby-Doo.
Scooby Doo
Yes. In the episode Night Terrors of Scooby Doo Mystery Inc., Shaggy and Daphne were kissing by the fire. Daphne thought she was kissing Fred, and Shaggy thought he was Fred. Shaggy said it was the best kiss ever.
Scooby Doo
No. But they are not alive. They are cartoons - drawings created by Iwao Takamoto.
Shaggy's age has never been revealed or mentioned in any Scooby-Doo episode, movie, etc.