bson.errors.InvalidDocument: key '$numberDecimal' must not start with '$' when using json

One more roll of the dice from me. If you are using schema validation as you are, I would recommend defining a class and being explicit with defining each field and how you propose to convert the field to the relevant python datatypes. While your solution is generic, the data structure has to be rigid to match the validation.

IMO this is clearer and you have control over any errors etc within the class.

Just to confirm I ran the schema validation and this works with the supplied validation.

from pymongo import MongoClient
import bson.json_util
import dateutil.parser
import json

class Film:
    def __init__(self, file):
        data = file.read()
        loaded = json.loads(data)
        self.IdTitulo  = loaded.get('IdTitulo')
        self.IdDirector = loaded.get('IdDirector')
        self.IdDecimal = bson.json_util.Decimal128(loaded.get('IdDecimal'))
        self.IdNumber = int(loaded.get('IdNumber'))
        self.IdDateTime = dateutil.parser.parse(loaded.get('IdDateTime'))

    def insert_one(self, collection):
        collection.insert_one(self.__dict__)

client = MongoClient()
mycollection = client.mydatabase.test_dec

with open('c:/temp/1.json', 'r') as jfile:
    film = Film(jfile)
    film.insert_one(mycollection)

gives:

> db.test_dec.findOne()
{
        "_id" : ObjectId("5eba79eabf951a15d32843ae"),
        "IdTitulo" : "Jaws",
        "IdDirector" : "Steven Spielberg",
        "IdDecimal" : NumberDecimal("2.33"),
        "IdNumber" : 8,
        "IdDateTime" : ISODate("2020-05-12T10:08:21Z")
}

>

JSON file used:

{
    "IdTitulo": "Jaws",
    "IdDirector": "Steven Spielberg",
    "IdNumber": 8,
    "IdDecimal": "2.33",
    "IdDateTime": "2020-05-12T11:08:21+0100"
}