I did a stupid thing and started with the last puzzle. This was pretty challenging and it felt great to solve it. However, it made the other puzzles seem really easy and/or simple.
A system where you have to at least try the first puzzle to unlock the second one and so forth could give the progression a bit more structure, while still not be punishing to players who gets stuck on a puzzle.
Otherwise a fun demo, the character felt great to control, it was easy to understand all the mechanics and so on. The lack of sound felt a bit awkward.
Keep up the good work.