In what way is homologous organs evidence for evolution?

Homologous organs are the organs that have different functions but they are believed to have originated from a common ancestor because of their basic structure of bones. Thus if homologous organs are present in different organisms, it can be inferred that they have same ancestors which provide evidences for evolution.

Example- forelimbs of humans and forelimbs of frog; they have different functions but they have same basic design which tells that they have a common ancestor.