After many retries, i managed to get all success, but the Chapter 2 boss (i didn't retry it yet).
Keep in mind i'm not usually a puzzle-gamer, so that's not helping. You should collect feedbacks from more advanced players with these skills. Everything i say could only be because i'm pretty bad at this genre.
It's fine, not to succeed on first attempt, but at this stage of the game (one playable hero, first time with a shield), it might be "too difficult". It seems there are not enough possibilities to win a level. Surrounded may be the most difficult to get a Perfect i think. I tried maybe 1 times.
I wouldn't mind a 1-or-2-solutions-only-level later in game, but at first, i think there should more "obvious", especially when you just start the game, and are just given a new hero to play with. You need to keep the new players in, and at same time, you want the dedicated too. Tricky balance !
As for what to actually change, that's hard to tell. Everything is so linked together, changing one thing (move a drudge, change a tile...) may "break" a level. Maybe start with a simple advice, "don't try to kill them all". also, for Surrounded level, "breach the bridge" or something. My success involved using the archers to kill the two drudges at the north, and avoid the two at the south. But before eventually do it for real, i needed to try a lot of different positions. Also in Surrounded, unless i've missed something, the two pikes are useless, so maybe not that bad to remove them, to avoid confusing new players with an already trick level.
I really like the game, i'm very exited to see the next updates, and observe the game growing in the coming months !