Humans originated in Africa, and all non-Africans are descendants of a small number of Africans who migrated out of Africa 60,000-70.000 years ago. Many of these people still look very much like Africans because they changed little since they migrated out of Africa, because their ancestors ended up in places with similar climates as Africa, such as New Guinea, SE Asia, Papua and Australia
Europeans, and NE Asians, OTOH, have changed because they adapted to cold climates by evolving straight hair, lighter skin tones, shorter arms and legs, more rounded torso, taller and narrower nose bridges, thinner lips, more facial and body hair, and more fat under the skin. The Europeans and NE Asians (China, Japan and Korea) descended from Africans who stayed in Central Asia for about 20,000 years before migrating again. Central Asia is cooler than Africa, so some of these adaptations to cold climates first evolved in Central Asians. Europeans and NE Asians therefore are similar because they inherited some features from their shared C. Asian ancestors. and they then evolved similar features independently by adapting to cold climates of the last ice age. .
Further, humans have not stopped migrating since then, and we have NE Asians migrating south to interbreed with SE Asians and their descendants have a mix of cold and warm adapted traits and a mix of genes. Central Asians and Europeans too have migrated to parts of East Asia. Europeans also migrated to the Middle East and North Africa, and later some of the Middle East people migrated back to Europe and to North Africa. For example, Italians from the southern part of their country are more closely related to people from Turkey, Iraq and Iran then they are to the northern Italians, who are more closely related to western Europeans like Germans, British and French. Because of such mixing it is difficult to find genes or traits that can be used to identify the people from one region vs. another. What we do have are mitochondrial DNA and Y chromosome markers that can trace a person's ancestor to a particular region, but these markers cannot be used to define races, since they do not produce the raical characteristics thaqt people notice.
Because scientists cannot come up with any good way to divide the human species into different subspecies or races, they have stopped trying.