Octopuses are smart, but I've yet to see anything that suggests they are smarter than dolphins or whales.

I've heard that the biggest limiting factor in octopus ocean domination is their short lifespans. Tool use, building structures, communication, facial recognition, multiple brains, it's all there.

https://www.nhm.ac.uk/discover/octopuses-keep-surprising-us-...

Female octopi also die reproducing. Knowledge cannot be passed from one generation to the next. Everything they know is either instinctual or learned.

Both whales and prairie dogs turn out to have rather advanced degrees of verbal language capability, more complex than any of the Great Apes bar homo sapiens. Crows somehow culturally remember the face of an antagonist multiple generations later. Almost every highly social vertebrate has degrees of intelligence that would get you burned as a witch if you'd suggested it not too long ago, in the era when "Fishes clearly don't feel pain" was just a cultural default assumption.