You're no amateur if you've already defeated 21 simple monsters. You appear to be in good shape; yet, in order to achieve a larger goal, you must improve your reaction speed. The first ten percent or so of the level is self-explanatory; simply work on the little ship areas that are upside-down and right-side up.
It's simply a matter of getting used to it. I wouldn't call myself a pro; rather, I'd call myself a'veteran,' as I've been playing since the fall of 2015. And, believe me, I've given up on many difficult levels, but if that hadn't happened, I would have completed them.
You can do it, too. Practice various skills such as straight flying, memorizing various patterns, and so on.
One of the hardest levels I've beaten, ZenthicAlpha's Supersonic, has a large memorization portion near the end, which is a fantastic example.
All game modes, such as cube, ship, ball, UFO, wave, robot, and spider, should be practiced. Refine your reaction speed by moving between confined spaces, reviewing different patterns, and practicing what you've already learned. The more you focus on improving yourself, the faster you'll get there.
To beat the most tough stages, you must develop the necessary talents. And skills are honed over time as a result of practice. Being a pro, on the other hand, does not happen suddenly. If you've beaten a lot of demons, start with the simple ones and work your way up to the more difficult ones, such as medium, hard, and insane.
After you've learned professional talents and defeated a large number of demons of various difficulties (easy, medium, hard, insane), you can begin practicing the incredibly difficult ones.
You must, however, work your way up. If you only fight 5 easy demons before trying to beat the game's hardest levels, they'll look insurmountable. As I already stated, I have given up a lot, and I believe I would be a much better player now if I had persevered all of those times.
Make sure that doesn't happen to you. Every Geometry Dash level is reachable with patience and effort. I may not appear to be a Geometry Dash fan, but I am. I've been playing since version 2.0, and I've given up several times. I just started hunting demons with the release of version 2.1. It's just that going from simple demons to Frontline isn't a good idea. You'll merely become frustrated by your lack of ability. So far, I've defeated 4/5 of the demon gauntlet and 22 demons, generally easy-medium ones. (Two of them are hard devils.)
Work on a different level. Try out the demon gauntlet and, if you haven't already, complete all of the official demon levels to get a sense of the many types of demons (skill, memory, memory-skill, and so on).
Beat the levels in order, from easy to medium to hard to mad to extreme if you're good enough. Playing the same simple demons over and over won't get you anywhere. You will improve by progressively defeating demons of increasing difficulty.
Obviously, you can, but it will take time and careful play. There is a practice mode in Geometry Dash to help you improve your skills on a certain level.
It is, however, preferable to play on a PC with a larger screen. This can be installed on a Windows or MacOS computer. So, downloading Geometry For PC and practicing on a larger screen should definitely help.
Try the NC devils; they'll be of assistance. Problematic, Infinite Circles, Ultra Paracosm, Fear Me, Jawbreaker, Nine Circles, Classic, Fairydust, Poltergeist should be played in this order. Then try out 8o and other Zobros demons, who will also help you improve your skills.
Also, for your created levels list, you should try making a copy of the level. You can use this to see the level and practice it piece by piece. Some sections will be more difficult than others.