Uhm, excuse me, that is clearly a walrus.

C++’s mascot is an obese sick rat with a missing foot*, because it has 1000+ line compiler errors (the stress makes you overeat and damages your immune system) and footguns.

EDIT: Source (I didn't make up the C++ part)

i guess "beaver" would've been kinda awkward with today's connotations with shaving the beaver etc.