I think you’re right but it’s not just speech. Wouldn’t these markings indicate some capability for abstract thought? Abstraction allied with speech is really what separates us from other animals.
I sure you’re right. Abstract thinking for sure. Our big brains (including Homo Erectus) required family and “tribe” relationships that were pretty complex. Most kids in most species are ready to go after a year or two. Our brains aren’t formed by then.