How to create custom array fields?

Using these docs, how can I create custom array fields?

I find the default array field UI really unintuitive in terms of creating an array field that basically has just one text field:

{
      name: "credentials",
      type: "array",
      fields: [
        {
          name: "name",
          type: "text",
          required: true,
        },
      ],
    },