Don’t give up.
As someone who converted from a compound to a longbow a few years ago I understand your frustrations. You will have to adjust your expectations as you begin this process. While you and I could both cut fletchings any time with a compound, it should have been that way due to all the mechanics, aiming points, mechanical release, etc. In other words, it couldn’t not be that way due to the machined-in and foolproofing of it by design. As a result, it is man and machine entering the woods, or backyard.
With a trad bow it is man and his skills entering the woods, or shooting in the backyard as it were. While the trad bows today are excellent, they can only do what you make them do. Conversely, the compound bow was very forgiving and could at times do what the shooter was unable to do on his/her own, again by design.
I shoot instinctive, but it fits me. Like Jason said, try other methods of “aiming” and see if one of them fits. But, please do not give up yet.
I can tell you that after a few years following my change to trad bows, I can shoot out to 22 yards with my longbow almost as well as with my former compound. It took a while to get there, but it is so much more fulfilling and thrilling! Sound advice (like from the good folks on this site), proper tuning of your setup, and practice are the key, but relaxing and enjoying it can accelerate your progress greatly. Relax and have fun, don’t overthink it. Most free throws at the end of a ballgame are missed due to nerves and overthinking it, not form, practice, or ability.:D
And remember…there are good shooting days and bad ones, just like anything else.:?