Express server is not deploying properly in Vercel

This is the first time, I tried to deploy my express server on Vercel. But, there are some issues probably. It didn't deploy correctly, I'm not sure why. However, localhost is running successfully. Getting 500: INTERNAL_SERVER_ERROR everytime.

I don't have any .envfiles as it's a practice project.

What I have tried:

package.json

  "name": "assignment-1",
  "version": "1.0.0",
  "description": "In this project, I have written the first assignment of Programming Hero.",
  "main": "index.js",
  "engines": {
    "node": "14.x"
  },
  "scripts": {
    "start": "node index.js"
  },
  "keywords": [
    "server",
    "javaScript",
    "node",
    "express"
  ],
  "author": "Riyad Hossain",
  "license": "ISC",
  "dependencies": {
    "express": "^4.18.1"
  }
}

vercel.json

  "version": 2,
  "builds": [
    {
      "src": "./index.js",
      "use": "@vercel/node"
    }
  ],
  "routes": [
    {
      "src": "/(.*)",
      "dest": "/"
    }
  ]
}

Here is the response I found: