Question, What Should We Do If Aliens Want to Colonize the Earth?

In 2050, with the emergence of extraterrestrial civilizations, humans are full of expectations and send messages to extraterrestrial civilizations. Extraterrestrial civilizations respond. However, only a large number of alien armies respond to humans. Only then did humans understand that extraterrestrial civilizations responded to humans with an aggressive mentality. Humanity has urgently formed the United Earth Army to prepare for war with extraterrestrial civilizations, but everyone knows that in the face of technologically advanced aliens, what ability does humankind have to fight back? However, with the emergence of the protagonist Chen Jia, all this may change. This novel and its characters are purely fictitious. Any similarity is purely coincidental and should not be imitated.