A lot of people might say that Willie the Wildcat is the mascot of nightmares because he is a human body with a Wildcat head, but it is a fun concept. Seeing him dress as a football player, basketball player, or baseball player brings, yes, a human aspect to him.
Willie also has his signature moves including his K-S-U chant where he spells out the letters using his body. The alliteration of Willie the Wildcats is fun and makes him recognizable around college sports.