There are several mammals that have larger brains than humans. Among Extant Animals, examples are;

*sperm whales (biggest brain in the animal kingdom)

*gray whales

*blue whales

*orcas

*humpback whales

*bottlenose dolphins

most of the other big whales and dolphins

*elephants

Among Extinct Animals

woolly mammoths

Neanderthals

Surprisingly, walrus brain sizes come close to human brain sizes. I would suspect the same to be true for cave bears