I am going to guess that it is Basjoo. There are a lot of different kinds of bananas but only a few widely available from nurseries. If your friend were a collector of strange plants far and wide who knows what kind it is. But if they likely bought it at a local nursery, then it will be one of three likely. Blood leaf, Dwarf Cavendish or Basjoo. By color it's not Blood leaf. DC and Basjoo can look similar but have tell-tales. The DC can have splotches on the top of the leaf when young. It also tends to have a redish stalk and it is edible meaning you should not have found a seed in the banana. Basjoo is an entirely green leaf but can have a hint of red on the leaf mid-rib. It's stalk should be green. It is cold hardy and ornamental so if you did take a banana you could have gotten a seed. Also, DC=red/pink flower and Basjoo=yellow flower. You wouldn't want to risk your only plant but if you test and find out it is Basjoo/cold hardy we can keep them in the ground here in 6a in KS.