That's the same toothy smile a silverback gorilla flashes as a final warning before it wears your corpse as a fun hat. Aside from his dystopian nightmare-verse where sentient dogs enslave humans and sadistically carom them all about the space-time continuum, there's absolutely nothing creepy about Sherman. HE'S JUST A CHILD IN GLASSES WEARING A WHITE T-SHIRT FOR FUCK'S SAKE. How do you screw that up? Why, by giving him the compound eyes of an insect:
"Head houses up to 100 bees!"
Again, here is the most no-effort costume in existence rendered uncomfortable and unnerving. (This is a theme we will keep revisiting.) It's like if all Harry Potter costumes came not with coke-bottle spectacles but with Daniel Radcliffe's yowling latex death mask.