The problem is that your brain has different levels of "person" recognition. Your brain tries to simplify stimulus down for quick reaction times, so while you may be able to logically deduce that Bugs Bunny is a cartoon rabbit and therefore not a person, his features still check enough of your brains "person" boxes that at a quick glance, he appears human enough.
Think for example, why do you see this as a face?
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There's nothing face-like about it, it's just a pair of dots and a curvy slit. But you can put a pair of dots and a curvy slit on almost anything, and suddenly, it's a face.
Likewise, adding a head/neck/shoulder and hips/butt to an object will humanize it further, which is often the difference between 21st century anthros and earlier cartoons.
The Tusken Raiders are a good example of this actually because even though they are actual people, they don't check the brain's boxes for humanness. Loose clothing and a mask hides them from us. Bird anthros are also difficult because bird beaks don't look enough like human mouths without some extra work, except for duck bills, which is why there are so many cartoon ducks.