Hey there, I have a piano channel too and have a ton of friends that do too.
Just make your thumbnails nice, clean, and unique. All your video thumbnails look the same, honestly. You should be able to clearly tell what the video is about, as well as have it catch your eye.
Also keep an eye on your video title format, it can make a huge difference.
You're very talented! It's obvious you're passionate about piano and you've got a great range of styles available, which will appeal to a wider audience.
I think improving on your thumbnails and adding more playlists for artists as you go is the thing to focus on most. Make sure you're using the original artist's name and song in your SEO as that'll help you massively. Good luck!