Nice little game! love the wall texture no idea why but its really nice when your jumping your way up. I would say since its a very simple game mechanic to tell the player at the start what to do. I was jumping just ones and dying for a few times until realizing i can jump multiple times in a row.
And it might be a bit cliche but some kind of lava/danger as an intensive for the player for wanting to go up.
The controls did feel very smooth and as a first try of a unity game its great :)