New Posts are those that you have not viewed, or have been updated with new replies since you last viewed that thread. So, New Posts can be new threads, but can simply be new updates to what can be older threads. Sometimes you will see really old threads (15 years or more), which have been updated, usually a new reply. (Probably why the name is "New posts")
So, the new threads are sorted with new responses to "less new" threads, in the order of receipt.
If you just want to look at threads with no replies...
Top of this page, first menubar starts with Front Page, Second menubar starts with Home. There's a dropdown there - click on that dropdown. 5th on the list is "Unanswered Threads" - and you may find relatively old threads with no responses.
BTW, when you spend some time here, you will occasionally see new threads with dozens, sometimes hundreds of responses, literally within a few minutes, for very hot issues, or basic info where a lot of Mac users have quick input.
AND, there's threads, maybe with a lot of views, but no responses posted, even after several years.
(dwfaust beat me out with the simple answer to your quest...)
