The US and Soviet Union had to start from scratch with their respective manned programs. Not only were their booster limitations (more for us than the Soviets) that limited vehicle mass, the basic technology and techniques for manned spaceflight had to be invented. Back in 1961, there was serious scientific debate about whether humans could even survive in space. Orbital maneuvering, docking and rendevous, long duration spaceflight, EVAs - all of that had to be invented.

The Chinese are smart enough to know what technology can be adapted or licensed for their purposes rather than starting from scratch. They have a powerful booster (with substancial growth potential), they licensed some good Russian technology (not an oxymoron at all when it comes to space systems), and built a vehicle well suited for their purposes with some unique capabilities.

When China started to build their own aircraft, they didn't go back to the Wright Brothers. They were able to build upon decades of aeronautical engineering experience. The same applies to their space program. Why recreate Project Mercury or Vostok to relearn manned spaceflight when they can build upon decades of our experience? They're not dumb.