Ariana Greenblatt has been surprised by her own success. The 16-year-old actress feels “grateful” for everything that she’s managed to achieve in her career, and Ariana has insisted that she doesn’t take any of it for granted. The Hollywood star told PEOPLE: “I take every opportunity that I get and [I’m] very grateful for it. “I never expected any of this to happen, and I don’t know what’s to come either. I’m just living in the moment.” Ariana thanks her family for helping to keep her grounded amid her meteoric rise. The movie star said: “I wouldn’t be who I was if I wasn’t close with my famil…