I know the majority of you are thinking "what an idiot of course you can improve" - Show me a graph of a player who has consistently improved over time. It doesn't exist. It's usually rapid increase or decrease at the beginning then just hovering around a rating forever. Give me a player profile graph and show me sl, long term improvement
I personally have improved in the last two months but it wasn't very quick i had to play thousands games to see any really change or improvement, I only use two openings and have only used those two openings. I play the same first three moves almost every game for the last couple thousand games but have gradually gained elo based on pure chess development and an increase in understanding. There is a cieling for everyone in everything, that being finite always is defined by limits that are defined. The climb; the aspiration to learn and/or grow is what makes learning/playing chess, lifting weights, studying a field, painting, or anything else worthwhile in the first place. I think your issue with being unable to improve/enjoy has nothing to do with the game itself and everything to do with how you approach chess and your appreciation of the game.
Oh yes you can improve at chess, I have played for over 50 years and I learned more in the last ten. Playing here, Lichess, and Chess Tempo. And most of that learning practicing the puzzles. Yes, there is probably a Peter Principle for all of us, but I am not there yet.