Why are human beings,who look so different from each other in terms of size,colour,and appearance,said to belong to the same species?

(N/A) species is defined as a group of organisms that are capable of interbreeding to produce fertile offspring.
Skin colour,physical appearance,and size are all variations of features present in human beings.
These features are generally influenced by environmental factors and genetic variations within the population.
Although different human populations exhibit these variations,there is no biological basis for classifying them into different species.
Since all human beings,regardless of their colour,size,or appearance,are capable of interbreeding and producing fertile offspring,they are classified as a single species,$Homo$ $sapiens$.