1. my bad, I just didn't play enough
2. I see that door not working as a new mechanic, it is nothing you do, but it is a new obsticle you have to deal with and in a puzzle game where you need to figure out the rules yourself. It being the thing you can ignore isn't a thing the player will know, because who knows, maybe it blocking you is only conditional and you somehow can go through it?
3. Yea, the numbers really made me feel like I need to follow the order, especially as the first two levels seem like intoductory levels
4. My bad then
5.I'd say that the wordless solution is the ideal one (at least for the type of game I enjoy). But in a jam it can be quite hard to do it properly, so it's hard to say when to use words.
I really need to try this again and ignore the level numbers!