No worries. Well i think personally each level should bring something new, so some new kind of mechanic or challenge and a lot of the early levels just repeat the same concept. For example: in my game skullface, the level structure was: introduce a new mechanic in a simple way, next level do it with a bigger challenge, and the third level do that mechanic but with another mechanic also intertwined - it was inspired by Portals dev commentaries so theres new challenges every level and a new mechanic every 3 levels. I also group mechanic types into worlds (first is basic, 2nd mostly jetpacking, 3rd is more puzzle themed) to add more variety too.
Yeah that's a way to do it, adding mechanics. Many other games, though, rely on limited mechanics like the game stephen's sausage roll, for example, which is pretty long but has simple mechanics and doesnt introduce any new in the whole game. Yet it remains challenging. I was aiming for something more like that. I understand it can come across as boring or repetitive, though.