Can a literal in RDF be seen as an "entity"? Coming from a background in Domain-Driven Design and Entity-Relationship Model this feels a bit weird.
According to https://www.w3.org/TR/rdf11-concepts/#resources-and-statements this is indeed the case:
Any IRI or literal denotes something in the world (the "universe of discourse"). These things are called resources. Anything can be a resource, including physical things, documents, abstract concepts, numbers and strings; the term is synonymous with "entity" as it is used in the RDF Semantics specification [RDF11-MT].
RDF11-MT does not contain a definition of the term "entity".
Then, https://kgbook.org/#sssec-directedelg does not explicitly mention the term "entity" for literals:
The RDF model defines different types of nodes, including Internationalized Resource Identifiers (IRIs) [Dürst and Suignard, 2005] which allow for global identification of entities on the Web; literals, which allow for representing strings (with or without language tags) and other datatype values (integers, dates, etc.); and blank nodes, which are anonymous nodes that are not assigned an identifier (for example, rather than create internal identifiers like EID15, EID16, in RDF, we have the option to use blank nodes).