I see all aliases besides the home page alias (At URL bar) Why is that? I mean, why when I click the home page link at main menu, it is only the site's URL (www.example.com), and not the exact URL of the home page (www.example.com/Decorations-for-all-houses) that appears? how can I make the full URL appear at the home page?

It should be noted that this is the only page with this problem; in all other pages, the FULL URL is always displayed.
If you set your site home page "Decorations-for-all-houses" (or perhaps lowercase would be less confusing) at admin/config/system/site-information, any home link provided by core, contrib modules, themes etc. will point to the right page.

You can edit any link of your main-menu including the home link at admin/structure/menu/manage/main-menu. The default link for home is &lt;front&gt;
which will point to your assigned home page, but it can be any path, including "decorations-for-all-houses".

Themes typically implement their logo link so that it points to the home page without the path, so you would have to edit the theme.

The above (hopefully) covers any case where users already on your site click a home link or logo. But what about visitors clicking a link outside of your site, like Google, or typing the domain name? For redirecting them from www.example.com to www.example.com/decorations-for-all-houses something like the Global redirect module probably would be able to do that.

What people usually seem to want, is just the opposite, redirect from the long url to the root. It might be confusing to visitors if they never can't get to the www.example.com even if they want to. This is what visitors expect to see as the home page url.