Many have wondered the same. I personally think Brandon Frasier's perspective in the film, "Encino Man," was quite apt.

The late Phil Hartman’s exploration as Unfrozen Caveman Lawyer was also trenchant and emotionally gripping

Of course she would be able to communicate. Cats and dogs can communicate to us.

Ok, communicate using complex language. She's not going to be picking up English at even a basic level.

Humans were speaking by 42,000 years ago. And even if not, she would have all the physiological equipment, unlike Koko.

Because she's a worm.

Why not? She probably already speaks more than one language, and they're probably both more complex than English. Many people learn languages quite unlike their native language late into their adulthood, but she's probably fairly young.

You can also watch Torchwood episode on this topic. It was beautiful.

Particularly a pre-Homo Sapiens Sapiens human...

42,000 years ago would be essentially equivalent to a modern human, physiologically.

All kinds of new fun diseases, probably.