It's tool use and language that differentiate us. Other species have one but not both. Learning is much more efficient when communicated rather than done in an isolated vacuum and all the knowledge in the world is useless if you lack fine motor control manipulation to take advantage of it.

How do you know crows and dolphins lack language? Because they don’t use a syntax like ours?

A theory is that dophins communicate by transmitting 3D information. They see with sonar and can use the same mechanisms to transfer 3D information. Probably vastly superior to the grunts of us apes for many tasks.

I think the implication was dolphins have language but not tool use.