object/washday/1 matches the site

public static HumanMadeObject Washday_1_Influenced()
{
    var washday = new HumanMadeObject()
        .WithContext()
        .WithId("https://linked.art/example/object/washday/1")
        .WithLabel("Wash Day")
        .WithClassifiedAs(Aat.Painting, Aat.TypeOfWork);

    washday.IdentifiedBy = [
        new Name("Wash Day").AsPrimaryName()
    ];

    washday.ProducedBy = new Production()
    {
        InfluencedBy = [
            new Person()
                .WithId("https://linked.art/example/person/whomer")
                .WithLabel("Winslow Homer")
        ]
    };

    return washday;
}

• Metatype classification The second argument classifies the first, not the object: WithClassifiedAs(Aat.Description, Aat.Statement) says this is a Description, and Description is a kind of Statement. The Plain C# form shows the nesting.
• Role shortcuts AsPrimaryName, AsAccessionNumber and AsSystemAssignedNumber each add a single classification, with the AAT terms Primary Name, Accession Number and System Number.

var humanMadeObject = new HumanMadeObject
{
    Context = ["https://linked.art/ns/v1/linked-art.json"],
    Id = "https://linked.art/example/object/washday/1",
    Label = "Wash Day",
    ProducedBy = new Production
    {
        InfluencedBy =
        [
            new Person
            {
                Id = "https://linked.art/example/person/whomer",
                Label = "Winslow Homer",
            },
        ],
    },
    ClassifiedAs =
    [
        new Type("http://vocab.getty.edu/aat/300033618", "Painting")
        {
            ClassifiedAs = [Aat.TypeOfWork],
        },
    ],
    IdentifiedBy =
    [
        new Name("Wash Day")
        {
            ClassifiedAs = [Aat.PrimaryName],
        },
    ],
};

Generated from the object the example builds: every property that is set, as object initialisers, with the vocabulary constants where a term is in the registry. The fluent helpers are a convenience, not a requirement; this form and the one as written produce the same JSON.