xcode - 変数の使用時にSwiftUI Observableが更新されない

Question

何らかの理由で、Observable のオブジェクトを変数に割り当ててから変更すると、ビューが更新されません。しかし、インデックスで直接アクセスすると、次のようになります。

動作しません:

var people = self.mypeople.people[0]
people.name = 'test'

動作します：

self.mypeople.people[0].name = 'test'

私の推測では参照に関するものですが、よくわかりません:(

コード例:

//: A UIKit based Playground for presenting user interface

import SwiftUI
import PlaygroundSupport
import Combine

struct Person: Identifiable{
    var id: Int
    var name: String

    init(id: Int, name: String){
        self.id = id
        self.name = name
    }

}

class People: ObservableObject{
    @Published var people: [Person]

    init(){
        self.people = [
            Person(id: 1, name:"Javier"),
            Person(id: 2, name:"Juan"),
            Person(id: 3, name:"Pedro"),
            Person(id: 4, name:"Luis")]
    }

}

struct ContentView: View {
    @ObservedObject var mypeople: People = People()

    var body: some View {
        VStack{
            ForEach(mypeople.people){ person in
                Text("\(person.name)")
            }
            Button(action: {
                var people = self.mypeople.people[0]
                // this howver works:
                // self.mypeople.people[0].name = 'Test'
                people.name="Jaime2"
            }) {
                Text("Change name")
            }
        }
    }
}


PlaygroundPage.current.liveView = UIHostingController(rootView: ContentView())