One thing I was surprised that you didn't bring up much was the history of the characters. Certain characters come from other areas and Mattel properties. Beastman was just a recycled Mattel concept from Flash Gordon. I'm always interested in the origins of characters and a lot of Mattel concepts.
You can almost see the similarities. Mattel just got out the old design pages and redrew him to fit the MOTU line. Paint him red and add a lion harness and you have beastman.
The same goes for Trap-jaw which was a Big Jim design, just tweaked. The same goes Battle Cat. The mold was from Big Jim toyline.