Bird and dinosaurs have a common ancestry. This fossil has teeth, although no bird has teeth. It has the skeleton of a dinosaur, but the feathers of a bird. It shows that there was a time when the difference between birds and dinosaurs was not obvious. Birds are the only remaining species from the dinosaur line.
Homology is a complicated concept.
It means that two structures are similar because they are related genetically. If two structures are similar but not related then they are only analogous. The wings of birds and insects are analogous. They both are used to fly, but in different ways. They are not related animals.