If you just want to store all your items and don't need to separate access or syncing some but not all to all your devices, you can stick with the default personal vault. No need to create an additional vault, then keep the personal vault empty (you're unable to remove that default vault, anyway).
For organizing things, you can assign tags. Don't use vaults for sorting and organizing, use tags instead. I recommend you download the desktop app, not use the website. The website is miles behind if it comes to usability. With the desktop and mobile apps, tags have better visibility and they can even be nested (use a / in the tag name to create a hierarchy).
Especially if you just started and need to import/edit many items, using the desktop or mobile app is way more user friendly than to use the website. If you consider using the app, do it now. Don't postpone it until you entered everything on the website.
