It was fun but it didn't wow me and I thought it was too easy

I totally agree. With the exception of BotW (except for the final fight...), I can't even remember the last time I bought a Nintendo game that actually challenged me. I guess kids these days are less willing to play games that challenge them.

If you want a good 2D platformer I highly recommend looking at Celeste or Pizza Tower. They're two very different games, but hands down the best platformers I've ever played in my life. (Very cheap, too). Celeste is the most mechanically interesting / challenging of the two. But every screen is a checkpoint, so when you die the penalty is losing like, 30 seconds max. It's a very chill yet challenging game.

And Pizza Tower has pretty typical mechanics (it's Wario Land but way more refined) but the art and sound design is incredible. It made me nostalgic for old cartoons like Ren & Stimpy and Courage the Cowardly Dog. The characters, sounds, and music are all so expressive I can't put it into words, you'll just have to look at the Steam page to see what I mean. It's also worth noting that there's no lives or health, so it's very chill. You're just playing for points like in old-school SMB. (Unfortunately it's not on Switch or any Nintendo products like Celeste)

Both games can be very easy or very difficult depending on what you want to achieve. The levels themselves aren't too crazy but they both have collectables and secrets that really ramp up the difficulty if you want to get them all. Celeste also has "B sides" for each chapter, which are bonus chapters where they crank the difficulty up to 11.