Hi there. I felt the exact same way, so I was very surprised that my acorn status says invited. It does seem like a lot of people that get into the program have very competitive grades/experiences. However, I believe that with determination, devotion and passion, anyone that meets the bare minimum admission requirements can get in.
I personally had quite mediocore grades myself. Last year gpa 76.5% and cgpa about a 3.2 (my half credit research methods course grade was 89%). I had about 1000 hours of direct social work experience through volunteering and about 1000 hours of extracurricular/leadership experiences from undergrad. I spent an immense amount of time and thought on my statement and assume that my references must have been strong.
If you want to pm me, I'd be happy to talk