I'll be echoing a lot of what's already been said here, but it's worth noting that this is a solid entry!
The jumping felt very responsive, although an explanation of potential player hazards and controls at the start would have been nice. It's obvious that a spike should be avoided, but when the golden sphere comes in I wasn't immediately aware that touching it would restart the game.
Some level variation could have been nice too - I learned the layout fairly quickly so if you wanted to expand learning how to do that could be a really good idea to keep the game engaging. Also some sound included would have been nice, you'd have a lot of room to do stuff there. As I said before, great attempt!