>>545412What the previous anon said. Most all of the Gundam anime are original except for outliers like Gundam: Thunderbolt, which is based off a spinoff manga.
And starting out with the original Gundam TV anime or trilogy movie recap movies is a decent way to start your descent into the Gundam franchise. You can then watch everything in the same timeline (which isn't really required besides direct sequels) or just do whatever you think looks interesting, really. Watching the original lays down all the ground rules for the franchise, which I think is important.
Also, this image is outdated by a few years, but hopefully it's helpful.