A Level 1 New Human battling a Level 1 zombie wouldn't pose much of a problem, but for higher levels, the flaws in human combat became apparent. Firstly, the body of a high-level zombie was completely weaponized. Particularly in Tang Ye's case - one of his hands was no different to having dozens of blades.
Moreover, zombies generally have superior defense and strength against new humans of the same class. In situations of single combat, humans couldn't gain an upper hand against the mindless zombies.
Tang Ye was different; he was a zombie possessing human intelligence. He could easily decipher the strategies of his opponents in any battle, avoiding potential traps. This made him invincible against New Humans of the same level.
