One big feature of Prolog that relies on lists are DCGs (Definite Clause Grammars)[0]. Lists are such a ubiquitous data structure that not having them in a language would just be painful.
Right. Developing natural language parsers was one of the main motivations for the development of Prolog. Natural language sentences are lists. List processing is something Prolog is excellent at. It's even better at it than functional languages because more things can be expressed in a tail-recursive way.
DCGs unsugar into lists, but the very fact that there's a non-list-based syntax (although lists are used for terminals, that could easily be avoided) shows that lists aren't actually essential. One has to pick some basic data structure, and lists are good for it, but they're not essential. (For example, one could use a lambda-calculus-based formalism, and then, if desired, encode lists in it in the usual way; or, as Prolog actually does it, encode lists as terms, as tempguy9999 (https://news.ycombinator.com/item?id=21772069) points out.