How can I mapped through this object from firestore?

Getting the users collection from firestore:

  useEffect(() => {
        if (currentUser) {
          const unsubscribe = db
            .collection("users")
            .doc(uid)
            .onSnapshot((snapshot) => {
          const arr = [];
          arr.push({
            ...snapshot.data(),
          });

          setUsers(arr);
          console.log(JSON.stringify(arr));
        });

      return () => {
        unsubscribe();
      };
    }
  }, [currentUser]);

This is what is shows where I console.log(JSON.stringify(arr));

[
  {
    1: { others: "books", items: { Item1: true, Item2: true } },
    2: {
      items: { Item3: true, Item2: true },
      others: "books",
    },

    displayName: Inigi,
    address: "US",
  },
];

I am new to react so this is quite confusing to me. How do I retrieve and display those 1 and 2?

I tried this but it does not work and I keep on getting an error:”

TypeError: _user$.items.map is not a function

 {user["1"]?.items.map((index) => (
                  <li>{index.Item1}</li>
                ))}

Answer

You can use {user["1"]?.others}