El elenco incluye papeles protagonistas y papeles secundarios.

Elenco means cast, especially the group of actors in a film, series, play, or similar production.

In Spain, elenco is a normal and fairly common word in cultural or entertainment contexts. Depending on the situation, you might also hear:

• reparto = cast
• el elenco de la película = the film’s cast
• el reparto de la película = the film’s cast

Both elenco and reparto are correct, though reparto is often very common in everyday use.

El is the masculine singular definite article, meaning the.

It is used because elenco is:

• masculine
• singular

So:

• el elenco = the cast

You cannot say la elenco because elenco is not feminine.

Because the subject is El elenco, which is singular.

• el elenco = singular
• incluye = third person singular of incluir (to include)

So the verb must agree with the singular subject:

• El elenco incluye... = The cast includes...

If the subject were plural, then you would use incluyen:

• Los elencos incluyen... = The casts include...

The personal a is normally used before a specific human direct object.

Here, the direct object is papeles protagonistas y papeles secundarios, which means leading roles and supporting roles. These are things, not people, so no personal a is needed.

Compare:

• Incluye papeles protagonistas. = It includes leading roles.
• Incluye a los actores principales. = It includes the main actors.

In the second example, a appears because los actores principales refers to people.

Papeles is the plural of papel, and in this context it means roles or parts in a production.

So:

• un papel = a role / a part
• papeles = roles / parts

Although papel often literally means paper, in film/theatre contexts it commonly means role.

Examples:

• Tiene un papel importante. = He/She has an important role.
• Buscan actores para papeles secundarios. = They are looking for actors for supporting roles.

Both are understandable, but they are not exactly the same in tone.

• papeles protagonistas = leading roles / protagonist roles
• papeles principales = main roles

Protagonista strongly suggests the role of the main character or one of the main central characters.
Principal is a bit broader and simply means main or important.

So:

• papel protagonista = lead role
• papel principal = main role

In many contexts, they can overlap, but protagonista focuses more on being the protagonist or lead.

In this sentence, protagonistas is functioning as an adjective describing papeles.

So:

• papeles protagonistas = leading roles

But protagonista can also be a noun:

• El protagonista de la película = The protagonist of the film
• La protagonista de la película = The female protagonist of the film

As a noun, protagonista can refer to a person.
As an adjective, it can describe something as leading or central.

Because they describe papeles, which is plural.

Agreement in Spanish usually works like this:

• singular noun → singular adjective
• plural noun → plural adjective

So:

• papel protagonista = leading role
• papeles protagonistas = leading roles

And:

• papel secundario = supporting role
• papeles secundarios = supporting roles

Both descriptive words must agree in number with papeles.

They both agree correctly with papeles, but they belong to different adjective patterns.

• protagonista is an adjective ending in -a that can often be used for both masculine and feminine in the singular, and -s is added for the plural:

  • papel protagonista
  • papeles protagonistas

• secundario is a regular adjective ending in -o, so it changes in gender and number:

  • papel secundario
  • papeles secundarios
  • escena secundaria
  • escenas secundarias

So the difference comes from the type of adjective, not from a grammar mistake.

Yes. A very natural alternative is:

• El elenco incluye papeles protagonistas y secundarios.

This is perfectly correct because the second papeles is understood.

The full version:

• papeles protagonistas y papeles secundarios

can sound slightly more explicit or balanced. Spanish often allows this kind of repetition, especially in more formal or carefully structured writing.

To some extent, yes, but the original order is the most neutral:

• El elenco incluye papeles protagonistas y papeles secundarios.

You could also say:

• El elenco incluye papeles secundarios y protagonistas.

That changes the order of the two types of roles, but not the core meaning.

You would usually not move things around too much unless you want special emphasis. For a learner, the original order is the safest and most natural.

Sometimes, yes, but incluye is the best fit here.

• incluye = includes
• contiene = contains
• tiene = has

For a cast or a list of roles, incluye sounds the most natural because it means that these elements form part of the whole.

• El elenco incluye papeles protagonistas y secundarios. = The cast includes leading and supporting roles.

Contiene is more often used for physical contents or components.
Tiene is possible in some contexts, but it is more general and less precise.

No. In this sentence, no article is needed before either phrase.

• incluye papeles protagonistas y papeles secundarios

This is a general statement about the kinds of roles included. Spanish often leaves out articles in this kind of broad, non-specific description.

If you added articles, the meaning could become more specific:

• incluye los papeles protagonistas y los papeles secundarios = includes the leading roles and the supporting roles

That sounds more like you are referring to a specific set of roles already known from the context.

It is talking about the roles, not directly about the actors.

That is why the key word is papeles:

• papeles protagonistas = leading roles
• papeles secundarios = supporting roles

If you wanted to talk about the actors themselves, you would say something like:

• El elenco incluye actores protagonistas y secundarios.
• El elenco incluye a los protagonistas y a los actores secundarios.

So here the focus is on the types of parts within the cast structure.