An antique photograph of a human soldier holding a Reclamation Society SMG from the Renaissance Period, dating it somewhere between 2121 and 2299. Note the lack of a formal uniform, which indicates that she likely lived in the then-chaotic wastes of Sichuan, China.The human species is incredibly diverse biologically, with countless races, many of which have histories stretching back to before the invention of a written language. In ancient times, such races were generally distinguished by skin color first and cultural identity second (due largely to the influence large-scale imperialism had on ancient human society). The transition from the the Classical period to the Dark Ages, however, brought upon the seclusion of such races. New mutations, however, continued to appear throughout the Dark Ages. This has left the human species with so many different individual races that, in humanoid-dominated parts of the galaxy, one could easily mistake them for entirely different species. However, races deviating so much from the "Baseline" pre-Dark Ages humanity are much rarer compared to those present before the end of the Classical period.
Human culture is equally diverse as human genetics, and perhaps more so. Classical practices, religions, and arts are still largely practiced alongside countless new cultures that arose in the eras following the collapse of Classical civilization. Going against the trend towards globalization in the Classical period, human cultures have remained largely independent throughout modern history. Despite the presence of a global constructed language, countless local languages remain, with Classical and modern tongues being spoken in massive numbers across the Earth. The cultural exchanges brought about by the end of the Dark Ages created modern cultures, which once again grew alongside re-emerging Classical ones to bring about an unprecedented level of coexistence never before seen in human history.
Of particular note in this Modern/Classical contrast is the difference between Lander and Seafaring cultures. Though such such a categorization is extremely broad, the massive dissonance between cultures found in both groups is too large to ignore. Lander culture tends to be more Classical, and is unique in the fact that religion is almost unanimous within it, while Seafaring culture is largely atheistic. Furthermore, Lander cultures are significantly more different from each other, as Seafaring cultures have engaged in more cultural exchange, which has made them closer in terms of traditions and values.
As a final note, humans are a durable species despite their appearance. Though a bullet that wouldn't pierce the scales of some alien monster could pierce through to a human's internal organs, they can take a lot of punishment before finally dying. Many species could be killed almost instantly by the trauma of losing a limb, but humans are known to take such an injury and continue to be fully active. In fact, in far too many events to count, humans have voluntarily chopped off their own limbs and survived. Their endurance is also exceptional, to the point that when put in primal conditions humans will simply follow their prey until it dies of exhaustion. Even some of the least physically fit members of the human species can bring about bursts of speed and power when threatened, and said bursts can allow them to completely ignore pain. In some situations, humans have lost one of their arms and continued to use weapons which generally require both, going on to defeat the enemy attacking them and even taunt them. Never,
ever underestimate a human.