Dear MichalRama,
Thank you for the reply.
From your screenshot, it's a default Document Library for this site, not a site page. They are different, and a Document Library can't be made as a homepage for a SharePoint site.
SharePoint Library: A SharePoint library is a specialized list specifically designed to store, organize, and manage documents and other files. While it shares many features with lists (such as columns and views), it offers additional functionality tailored to document management.
SharePoint Page: A SharePoint page is like a canvas where you can display information, such as text, images, links, lists, and libraries, in a user-friendly format. You can customize pages to create dashboards, report centers, or just general content pages that might contain web parts linking to other SharePoint components.
If you want to show documents on the homepage, you can Use the Document Library web part - Microsoft Support.
Sincerely,
Jazlyn | Microsoft Community Moderator