Similarities between seemingly unrelated organisms can be explained by darwin’s theory that organisms come from common ancestors. is it true or false?

Darwin's theory with relation to similarities amongst unrelated organisms looks at either similar form or similar function of appendages and from this it is postulated that some organisms have common ancestors based on these similarities. A broad example would be the fact that most vertebrates (organisms with spines) stemmed from one or a group of common ancestors, while invertebrates (lack of a spine) are related to common ancestor or groups of common ancestors. So the answer to the question is yes, it is true.