Answering questions about the recruitment of five types of troops

Original text of some friends' questions:
There are two things I don't understand: first, how can Zhao Dongping, with his qualifications, enter a fifth-category unit? Second, how can a squad leader at his age become Zhao Dongping's instructor at 37? He should be a soldier on special missions, at most a squad leader.
Yaoshao's answer:
Many friends have asked this question, so let's answer it here first. Zhao Dongping was not a soldier's child—simply put, he wasn't the son of a high-ranking official. The Category Five Special Forces were a special operations force that had normal training attrition rates on the training ground and, when necessary, would carry out special non-international missions. Without strong political background and considerable loyalty, they could not be admitted. It was absolutely impossible for him to join the Category Five Troops as a child; the only way was for two thousand years later, to improve combat experience, the Category Five Troops recruited a group of soldiers who had proven absolute loyalty to the Party and the people and possessed rich combat experience. Most of these soldiers came from the border garrison forces with Afghanistan and Afghanistan. They fought against Afghan guerrillas, Eastern Gunda, and Assan special forces on the India-Tibet border. Such overage trainees could no longer receive systematic training. The school would assign them to the best soldiers who had already been promoted to squad leaders, who would serve as instructors who crammed throughout.
Is that the explanation clear?
ps: Some people say I wrote Zhao Haiping like a god, but say it's too empty. I want to say a bit of caution: do you know the difference between professional special forces soldiers who have fired tens of thousands of rounds on a training ground and battlefield, and can easily disassemble any weapon without a manual, compared to those local units who carry guns every day but only do a handful of target shots and diligently practice grappling and hand-to-hand combat? Do you know the terrifying intimidation a veteran elite sniper or marksman has when fighting in jungle hills?