I meant real, quantitative, non-anecdotal evidence. Currently, we can prove with real evidence that a neural-network can form at least the basics of intelligence. The more neurons in the network, the more intelligent and sentient-like the entity will seem.

Humans are (roughly) at the top of the list of animals for their neuron count: https://en.wikipedia.org/wiki/List_of_animals_by_number_of_neurons

There are a few animals with neuron counts similar to ours, and I believe those animals could do everything a human could do and are every bit as sentient as we are.

In the list I linked, you see elephants are one of the only creatures with a higher neuron count than humans. Most likely, they have the mental capacity to build cars, planes, and eventually travel the stars. However, they lack other important biological features, unrelated to intelligence, that prevent them from doing so. For example, their size and the fact they have no hands.... makes it hard to create agricultural tools, or type on a keyboard.

So, yes, cetaceans and squirrels are sentient and intelligent. But their low neuron count make them less intelligent and less sentient. I believe intelligence and sentience scale exponentially with neuron count. As long as there are at least 2 neurons present, intelligence and sentience exists... albeit not to a significant degree. Modern day AI's have the neuron count of something like a dog probably. Would have to look into it more to compare them.