Unfortunately the main problem is chronic underinvestment by successive governments of all political inclinations. We tend not to fix our roof in the summer because we hope the other guys will be in government by winter when everyone inside is getting wet and they'll get blamed for the consequences of our decision. We've also made some poor choices historically around selling off national assets and questions of privatisation or public ownership.
This isn't unique to the NHS and ironically among the current Labour government the Health Secretary, Wes Streeting, is one of the few people suggesting significant changes that actually do make sense for the long term future of our country. Unfortunately a lot of them will probably require more than 5 years to implement and that puts the results over the horizon beyond the next general election. So the price for trying to "do the right thing" might be that he won't get re-elected to see it through. This enables the cycle of short-termism and lack of consistent investment to continue even though its horrible results are increasingly clear for all to see.
Ironically, that's not a problem in China, they have a one-party authoritarian state and can plan 10, 20 years ahead without worrying about elections or political instability.