"China Lands on Mars in Crowning Moment for Space Program

The success of the Tianwen-1 mission makes China the third nation after the U.S. and Soviet Union to land on the red planet"

https://www.wsj.com/amp/articles/china-lands-on-mars-in-crowning-moment-for-space-program-11621040108

Let's see..every generation, three nations battle in space to travel farther and farther with talks of colonization. Mars is so far that they all had to send robots to survey.

What if earth is a battle ground between different alien nations attempting to colonize it?

This would explain the different races easily. Not sure how itd explain the animals tho