Since this question seems to keep bugging certain game developers…
Well as so it happens I do in fact have the ultimate answer to that question!
They are…
wait for it…
Characters on a video game box art!!!
Dun-dun-duuuuuun!
This is your mind…
This is your mind blown!
(please be kind to me, I know I´m not that funny)
They look like:
I guess Steve Purcell got so much information about the game and had to do his best… 
Yeah, I never really questioned that myself. Maybe Ron would have prefered the actual crew of the Sea Monkey instead, who knows. But it never bothered me and still doesn´t.
In a related bit of trivia, the box art for Maniac Mansion was originally to include all the characters but for some reason Wendy and Michael were cut from the final version (probably for space reasons).
