There is this movie I saw with my dad back when I was still small (like 13 years ago or something). It's a relatively old animated movie, probably Japanese but can't remember to be honest.
What I remember about the movie is that the main character is a young cyborg boy and he is living in a futuristic world with a floating island above his own world. The floating island is mysterious and heaven-like and is connected to the world with steel beams/poles. These beams/poles have a defence mechanism to ensure that no one climbs up to the island (something like a big spiky ring moving up and down the pole knocking off all that's on there).
All the boy wants is to make it up there someday and throughout the movie you can see him trying numerous times and failing over and over and getting hurt like losing an arm and fixing himself again and again. Next to this boy there is also a girl that cared for him, not sure whether it was sister or romantic interest.