Json serializing in python - losing the variable names when it is serialized

Question

I am making a chess league to track elo and I am storing all the data in json files. However when I use:

    json.dumps((objectToSerialize, default=lambda o: o.__dict__,
                          sort_keys=True, indent=4, separators=(',', ':'))

The object I am trying to serialize:

    class Player:
        def __init__(self, rating, name):
            self.rating = rating
            self.name = name

instead of it making a string like this

    {
                "name": "jack",
                "rating": 1500
    },

it is like this:

    [
                "jack",
                1500
    ],

It is important that the values are given identifiers as when I read the data in the program, it cannot be understood.

Is there something I am doing wrong or is there a fix for this?