How do I save a new data to MongoDB?

I’m new to databases and I’m currently working on a Discord bot project. I followed a YouTube tutorial and decided to use MongoDB. However, when I tried to send data for a level system to the database using the save() method, I encountered the following error:

TypeError: level.save is not a function

---

messageCreate.js:

const { Events, Message } = require("discord.js");
const Level = require("../models/Level");
const getLevelXP = require("../utility/getLevelXP");

function getRandomXP(min, max) {
  min = Math.ceil(min);
  max = Math.floor(max);

  return Math.floor(Math.random() * (max - min + 1)) + min;
}

module.exports = {
  name: Events.MessageCreate,
  async execute(message) {
    if (!message.inGuild() || message.author.bot) return;

    const XPToGive = getRandomXP(5, 15);

    const query = {
      userId: message.author.id,
      guildId: message.guild.id,
    };

    try {
      const level = await Level.find(query);
      if (level) {
        level.xp += XPToGive;

        if (level.xp > getLevelXP(level.level)) {
          level.xp = 0;
          level.level += 1;

          message.channel.send(
            `@${message.member} have been leveled up to **Level ${level.level}**`,
          );
        }
        await level.save().catch((error) => {
          console.error(`[ERROR] ${error}`);
          return;
        });
      } else {
        const newLevel = new level({
          userId: message.author.id,
          guildId: message.guild.id,
          xp: XPToGive,
        });

        await newLevel.save();
      }
    } catch (error) {
      console.error(`[ERROR] ${error}`);
    }
  },
};

Level.js:

const { Schema, model } = require("mongoose");

const levelSchema = new Schema({
  userId: {
    type: String,
    required: true,
  },
  guildId: {
    type: String,
    required: true,
  },
  xp: {
    type: Number,
    default: 0,
  },
  level: {
    type: Number,
    default: 0,
  },
});

module.exports = model("Level", levelSchema);

---

After that error, I double-checked and found that no data had been uploaded to the database. My expectation is to make the data that I’m trying to save, is sent to the database.