I've watched all the Star Wars movies, but I never watched the animated series The Clone Wars. There are several references to characters from The Clone Wars and some of them even show up on Rebels. Versions of characters from the movies also appear in Rebels. Basically Rebels is the story of what is going on in the universe leading up to and during Rogue One. Fun Fact: A few of the Rebels characters show up in Rogue One. You have to have an eagle eye to see them, but if you want a heads up on when they appear, check out this interview with Lucas Film Story Group's Matt Martin on StarWars.com.
Initially Ezra is a whinier version of Luke Skywalker. He grows both in character and power as the series progresses. Kanan is a surlier version of Obi Wan Kanobi. He is a reluctant teacher and has a lot of anger over the destruction of the Jedi Order. Hera, Zeb, Sabine, and Chopper round out the cast nicely, each with their own set of skills. As with all the Star Wars movies, I find the droids to be the stars of the show and Chopper is no exception. He/it is a droid with attitude! There are only 4 seasons of Rebels; the last episode aired on March 5, 2018.
If you are wondering how all the Star Wars stories fit chronologically check out this Digital Spy article. The list does contain spoilers.
*There are a lot of different species in the Star Wars universe. Wookipeedia is a great place to go for information.
~Amy, Adult Services