I wonder why mainstream animated features have so few funny characters. This popular film had only one, which is shown above. She wasn't on the screen very long and had only two or three expressions that I can recollect but at least the film earmarked one character for comedy and we can be thankful for that.
The family in the film weren't intended to be comedians. They were dramatic characters with occassional slightly humorous moments.
Walt had a different idea about how to inject comedy into a feature. He threw in a bunch of clowns who slurped their soup, fought with each other and engaged in broad slapstick.
To balance out the comedy he made the mean character REALLY, REALLY mean. She wasn't neurotic or mischievous, she was downright evil. The extreme behavior of the witch created so much tension that we were glad when the slapstick scenes came up. Modern fims have mild, tepid villains and slapstick, with all its funny animation possibilities, seems out of place.
If the villain in the superhero movie had been stronger, then the film would have needed a more overt and funny comedy to balance it out. Maybe comedic characters a little like those shown above, or like George Liquor (shown below) or the animated equivalent of the characters in "Dumb and Dumber," or the dog in Clampett's "Hair Ribbin." I think the audience would have liked that.
As it was, there was no strong villain and therefore no truly funny comedy relief.