PHP MVC Namespacing and Aliasing

Question

I'm trying to learn PHP better my working on my custom framework (learning purposes) and I was wondering how can I implement namespaces with aliases (they're new to me). My "framework" structure look like:

app/
    controllers/
    core/
    functions/
    languages/
    models/
    vendor/
    views/
    .htaccess
    composer.json
    composer.lock
    config.php
    database.php
    filters.php
    index.php
    init.php
    routes.php
style/
upload/
.htaccess
index.php
robots.txt

In app/core folder I have files:

App.php
Controller.php
Filter.php
Functions.php
Language.php
Route.php
index.php

And my init.php file looks like:

<?php
    require "vendor/autoload.php";
    require "database.php";
    require "core/App.php";
    require "core/Filter.php";
    require "core/Route.php";
    require "functions/Common.php";
    require "functions/Validator.php";
    require "functions/Custom.php";
    require "core/Language.php";
    require "core/Functions.php";
    require "core/Controller.php";

Files from controllers/ folder extend Controller.php, and core/Functions.php extends core/Custom.php which extends core/Common.php How can I implement namespacing and alisaing so I can make my framework easier for maintaining and not needing to load every class with full namespace? Thanks in advance

Edit: Ok I've created a file controller.php in app/controllers/ with this code

<?php
    use App\Core\Controller as BaseController;

    class Controller extends BaseController {

    }

And in my App.php I added the following function:

    private function applyAliases() {
        foreach(self::$config['aliases'] as $file => $alias) {
            class_alias($file, $alias);
        }
    }

So in my config.php file i added:

/* Aliases */
"aliases" => [
    "App\Core\Language" => "Language",
    "App\Core\Filter" => "Filter",
    "App\Core\Route" => "Route"
]

Also, in Functions.php when loading functions i added another class_alias:

public function loadFunction(string $file) {
    if(!file_exists(App::$config['paths']['functions'].$file.".php")) {
        throw new Exception("File ".App::$config['paths']['functions'].$file.".php doesn't exists");
    }

    require App::$config['paths']['functions'].$file.".php";

    class_alias("App\Functions\\".$file, $file);

    return new $file();
}

Would this be the proper way?