What does the presence of homologous structures in different organisms suggest?

Homologous structure are similarities in bone structure between different species that might have different functions. An example is the human hand and a bat wing. Homologous structure can be opposed to analogous structure that are found body structures, in different species, that have the same function but different bone structure, an example are dolphins and sharks fins. If homologous structures are present in different species we can imagine that they come from a common ancestor