I am almost sure that there isn't a way to accomplish what you have in mind, at least not with a hidden page. What probably could work is sort of a splash page that is addressed through a line in the .htaccess file. This way a visitor to your site would, when opening your site, see the splash page first. On that splash page is a link that takes you to the actual homepage.
but don't want everyone to be able to go back to this page once they are navigating the site
That's not gonna work out using the website builder. Technically there are ways to realize such solution but using website builder that's nothing short of a miracle.