laravel 5.7登录程序问题

Question

I have been trying to figure out why is this happening ! I have used the laravel's built in authentication method ,my laravel version is 5.7 and DB is Mysql.The problem is that when I try to login , there is no reaction performed by the server , otherwise , the signup procedure works correctly .I have to mention that when I use these codes with another database built with migrations, everything goes well . Here is my model :

    <?php

namespace App;

use Illuminate\Notifications\Notifiable;
use Illuminate\Foundation\Auth\User as Authenticatable;

class User extends Authenticatable
{
    protected $table = 'person';
    use Notifiable;
    protected $guarded= [];
}

Here is my login controller :

<?php

namespace App\Http\Controllers\Auth;

use App\Http\Controllers\Controller;
use Illuminate\Foundation\Auth\AuthenticatesUsers;

class LoginController extends Controller
{
    use AuthenticatesUsers;

    /**
     * Where to redirect users after login.
     *
     * @var string
     */
    protected $redirectTo = '/';

    /**
     * Create a new controller instance.
     *
     * @return void
     */
    public function __construct()
    {
        $this->middleware('guest')->except('logout');
    }

    public function username()
    {
        return 'username';
    }
}

routers

<?php


Auth::routes();
Route::get('/', 'HomeController@index')->name('indexPage');
Route::get('/contact-us', 'ContactUsController@index')->name('contactPage');
Route::get('/about-us', function(){return view('pages.AboutUs');})->name('aboutPage');
Route::resource('/brands' , 'brandController');