Congratulations on your first level! This is OK for a first. I liked the screens with low ground and starry skies, like 1002x1000. But there were too many glitches, and some bad design decisions. The glitches were already outlined by GrayFace and lamarblake. Bad design decisions were, well, contrasting screens for one thing. 1005x1000 has dark skies, and the next screen is AIEEE, SUNLIGHT!, too abrupt.
And then there were some rather annoying no climb tiles. Why would you put them in 1003x1000? The player isn't likely to go back, and even if they do want to, why not let them discover there's nothing to do there at the moment? In 1005x1000 you could've simply closed some areas off, instead of adding no climb tiles. They just don't feel right, because the sole reason for their existence is that you took the easiest way to secure the challenge in that screen.
Then there was mixing of layer 3 tiles with transparent tiles, and the player can't easily distinguish between the two - almost never a good idea. (Unless, of course, it's a secret passage or something.) Leaps of faith are fun when you're going to the right, but they're no fun at all when you're going back, because going from 1002x1000 to 1001x1000 results in death - who would remember there's water at the right edge of the screen? The solution is to either put a few more savepoints in, or better, design the screens differently.