Needs a LOT of work
Ok, you have the template here for a decent game, but as it stands right now theres nothing at all interesting about it. There's no story for whats going on here, no proper goals or tasks. Theres no real sense of danger since the game is so easy. Add to that most of the "levels" don't have anything that could hrt or kill your character and all you're left with is walking from screen to screen.
There seems to be some kind of problem with the character as whenever you jump with him, he turns and you can basically end up with him walking along on his head, or along his side. This coupled with the fact that if you jump into a wall and hold the direction key into the wall means you can just stick to the wall Spiderman style means that there is some serious programming bugs that need to be worked out with regards to the controls.
The biggest thing you need to rectify here though is the complete lack of sound during the game. Nothing. Nada. Silencio. You really don't know how much ANY kind of noise benefits a game until you play through one in silence. Even a generic looping track of music would have been something to add in to break the silence. But if you want to improve on this properly, sound effects are a must. The sound of rushing water during the waterfall/river part of the game, a bubbling lava sound for the well lava obviously. Even a classic "jump" noise for your character to make everytime he jumps much like in classic platformer games.
There needs to be a source of conflict here too, some kind of story. Even if the story was something as simple as the guy was climbing a hill one day when he fell in a disused mine shaft or something and had to find another way out. Then have the crux of the gameplay being him trying to escape the mountain. Of course, you'd need enemies that wouldn't look out of place in a mountain cave so add enemies like spiders, rats and bats. Even if you were to rework the game you currently have but add these enemies to the levels that are totally bland and boring like 3/4 and have you needing to avoid them as you travel through the caves. Really, something is needed to spice this up a bit.
Like I said, this needs a LOT of work, but its not totally irredeemable and is a strong foundation from which a good game could grow. But you need to take the time to implement things like sound/enemies or really most people won't give this game a chance.