Many long-running anime start with filler or slow exposition. Episode 001 of Shippuden jumps directly into the Kazekage Rescue Arc. It respects the viewer’s time, immediately raising the stakes: Gaara, now the Kazekage, is in mortal danger. This is why "001 top" appears in searches—it is widely considered a perfect first episode.
Availability varies significantly by region, but many countries host various seasons of the show. animerg naruto shippuden complete series 001 top