REST API stored in a MongoDB Atlas Database
In general, I think the code looks pretty good.  I would suggest two changes:

Dry

In an effort to keep the code DRY, I suggest constructing the player dict in a function for that purpose like:

def player_to_dict(player):
    return {
        'name': player['name'],
        'position': player['position'],
        'nationality': player['nation'],
        'position': player['position'],
        'foot': player['foot'],
        'age': utils.date_to_age(player['birth_date']),
        'profile_img': player['profile_img'],
        'abilities': player['abilities']
    }


This takes out quite a bit of code from:

def get_player(name):
    try:
        player = db.players.find_one({'name': name})
        return jsonify({'result': player_to_dict(player)})
    ....


I like comprehensions:

Using a list comprehension and the new player_to_dict(), you can remove the explicit for loop and instead make get_all_players much smaller and looking like quite similar to get_player.

def get_all_players():
    try:
        players = db.players.find()
        return jsonify({'result': [player_to_dict(player) for player in players]})
    ....