It is possible to watch Shippuden without the first series and still understand what is going on. All you need to do is learn all the names and words for things and learn characters’ names.
I’m not joking. Seriously, don’t waste your time by watching the first series.
Everything is covered in Shippuden. Everything that is important and you need to know is revealed with flashbacks or dialogue. Especially towards the end of Shippuden, the studio decided they really liked flashbacks so shoved 15 minutes’ worth of flashbacks into all the episodes, even including flashbacks you’ve seen ten times before in previous episodes.
I haven’t seen the first series of Naruto except for the episodes with Itachi in (I really like Itachi). I’ve only seen Shippuden. I was confused at first, but my little brother explained everything I needed to know (not that he had to, it was all revealed later on). Once you know that Naruto is an orphan, and Sasuke’s older brother murdered his whole clan (minus Sasuke of course), you’re good to go.
Obviously my reasoning for watching Shippuden and not the first series isn’t normal. I didn’t watch Naruto for the story, I watched it for Itachi. I only had to watch 15 episodes of Shippuden to see Itachi, I would have had to watch a lot more episodes of the first series to see him.
Yes, you’ll miss out on character development, but Shippuden has character development too. If you watch the first series, Shippuden won’t be confusing at all. So it really depends on what you want to do. You might even have to ask other Naruto fans what happened when you’re confused. Plus, the first episode of Shippuden is confusing to everyone, regardless of whether you’ve seen the first series or not. It doesn’t make sense until further on in Shippuden.
Skip the first series and save time, and jump into Shippuden which is apparently a lot better. Risk being confused and not knowing what’s going on for a while. Or watch the first series (skip the filler, never watch filler), and have to sit through a lot of episodes which is covered in Shippuden anyway. It’s entirely up to you.