why everyone in this community is so skilled

The game is over 7 years old and has the tendency to bring back old players (once a GD player, forever a GD player). Naturally, these people have had time to play the game and get really skilled at it.

This is good news for you, because if you just play the game for a long enough time, you’ll also be able to beat harder levels.

Only really thing you can do is keep playing, you'll get better overtime if you do

don't worry you'll eventually get there, i once thought i would never beat clubstep and here i am

I only beat The Nightmare and half of Demon Mixed.

I'm a noob too ;)