i was reading an interesting breakdown of super mario world about how mario games achieve "fun while not too hard" (although marios are kinda easy still), and it basically works because mario is actually not just a platformer, but it's a fusion platformer-action game. there are levels focused on technical jumping, etc. but there are also levels more "action"-focused that deal more with fighting / dodging enemies.
a game with only one major mechanic cant do much other than linearly scale the difficulty, which is okay for arcade-type games, but in a long-form game, players either get fatigued, or adapt so it becomes monotonous. the idea with a fusion game is that the levels will constantly switch back and forth between focusing on the two different mechanics. this means that levels can be "challenging" even if they aren't technically becoming harder, because "switching gears" so to speak is difficult in and of itself. but the players will get greater senses of accomplishment / overcoming because when they do switch gears they'll be able to adapt to harder things a lot faster, because they technically already have most of those skills. basically you have two different difficulty curves which can go up and down and which interlock with each other which makes the game progression more interesting.
even in the context of a pure platformer, like jumper 2 has a good variety of different kinds of jumps (double jumpnig, wall-jumping, skid-jumping, etc). and there's enough variety where rarely do 2 levels in a sector feel overly similar to each other in terms of what they are testing out. meatboy has a lot of jumping hard stuff, but also a lot of avoidance / pathing hard stuff (moving blades, dodging rockets, etc). cuphead has shooting and jumping.
anyway idk if i explained that right and also if it's applicable to your game, cuz yeah you would probs just have to add a bunch of stuff. but yeha i think that's one way games can be somewhat "easier" / not ultra-technical, but still be interesting..... well i just read about it though *npc shrug*