What does it actually require to be able to play well?
It depends on what you mean by playing well I guess... reaching GM-level is very different from reaching a decent club-player level.
For the first one you likely need some talent as well as lots and lots of hard work studying chess and, importantly, a very good memory.
I have neither of those but have managed to become a decent club-player at least. I am the captain of my chessclub's second team in the Swedish division 3 (our first team is in div. 2). I have no reliable rating since I started playing rated games rather late and have yet to reach my real level. I am now at 1600ish and gain about 100 per rating period. If I'd venture to take a guess I'd say I'm around 1900-1950 ELO since I beat those ratings slightly more often than I lose to them.
Here are a few things I believe are generally useful to improving your level of play.
Make sure you think playing is FUN. If you don't, improving is hard indeed.
If you are not a member of a "real" chessclub, find one and join. If possible, find one where you have one or more strong player/s willing to watch your games and give you concrete tips on your games. Some clubs are very competitive and result-oriented, others are more casual and fun-oriented. I'd pick the second type if possible.
Play games with long timecontrols. In division games the timecontrols are 2 hours for 40 moves and 1 hour for the rest of the moves per player. If you think this is to long try to at least play some G60 (60 minutes per game and player). Playing more longer games will even help you more in 5 minute games than just playing 5 minute games alone.
In my case, I am simply not good at 5 minutes or less. My online rating dropped over 300 points when I practiced 5 minute games before a 5-min tournament. (I normally played mostly 15 minute games). Maybe you are the same way and will play better with more time.
Write down your moves and go over them afterwards. Where did I go wrong? Try to find a better move next time. The computer can be a valuable tool for this but much better is a good players input to explain WHY the moves were good or bad. Again - to do this you probably need longer time controls.
Learn important general concepts. Do you know what to aim for in an opposite castle position? Do you know when to trade pieces and when not to trade pieces? All these generalizations are relatively easy to learn and are true in most cases, even if there are exceptions of course.
Play many games. The more you play the better you will be.
Try to not focus too much on your rating. Your rating is a function of your level of play NOT the other way around.
If it is down to the intellect of the individual player then that kinda would suggest Im pretty stupid.
Chess is not an intelligence test. It combine many different abilities, for example pattern recognition, memorization and general knowledge of chess. Many of these abilities have little to do with intelligence, time management for example.
Lastly, at your rating I guarantee that you CAN improve if you really WANT to and have at least some time to invest. It's difficult to say anything specific without knowing more about you. If you want, we could play a few games someplace and I could give you more tips on your game. Let me know.
