What can I do with an original iPad mini?

I wanted to use my iPad mini (2012) just for Kindle. I had the Kindle app on it plus a book I was reading. But I couldn't download any more books. The message said it was full. It wasn't full. Almost everything had been deleted and accounted for less than a GB. I called Apple for help and was told to remove everything. I did, and now it won't let me even download Kindle.