This project is more stapling than sewing, but small upholstery projects are quite easy to do, and can be done with small amounts of fabric and padding. The padding for this project was mostly layers cut from an old quilt.
When you pull apart things like this you often find old repairs and layers of previous fabrics. It can be quite interesting to see the way they have been put together.
Yes good job. I also did this, would not know how to start if the seat didn't just come out. Mine did not have fabric but a pleather top, cold-foam layer, and a layer of krin (material made from palm leaves that looks like hay but bouncier).