Hi, not sure I understand well...but each category can be shown in menu and each category can have products. If you're talking about "the look" like ebay has, that is when you open ebay there are products already on main page, you can define one category to be opened by default when a user visits your site, you do that by going to Stores->Configuration->General->Web->Default pages->Default Web URL and insert permalink there. To find out the permalink of your page/category go to Marketing->SEO and Search->URL Rewrites and copy the "target path". Hope this helps.
