[the phantom]

Have we decided that a union is not possible without a true incarnate? I had always assumed that the other spider creatures were Ainu like Ungoliant, not mere animals (but certainly much less powerful Ainu compared to Ungoliant). If that were true, Shelob could certainly be rational.

If those other spiders did not have any heavenly origin whatsoever, I would say that she would not be considered to have sentience. She would just be a very smart and powerful animal.