Thanks for the explanation. It's really interesting to learn the thought process behind games. As someone who also made a puzzle game, I understand that getting the balance between tough and easy is difficult, and usually requires longer than 48 hours to do.
If this was my choice, I think you could afford to lose a couple of the puzzles. I think that your knowledge for level 2 is enough to take you across level 4. Potentially use level 3 to introduce a new mechanic, so you've got a little bit of what you know, and now something new. I think you can trust the play to understand early enough.
Having said that, making the game slightly easier for a game jam is a good shout, as it allows everyone to play through it. And the experience itself -- the graphics, the music, the atmosphere -- was really great.