The Cowboy Jedi.
That's how Kanan Jarrus was first introduced to us back in 2014, before Rebels came out and any of us knew how much of an impact it would have on our lives. And he definitely lived up to that moniker, even if he became much more Jedi than cowboy by the fourth seasons. But it's an interesting title for a character.
It's no secret that George Lucas, and therefore Star Wars, was heavily influenced by the American Western movie, the birthplace of modern conceptions of the cowboy. Star Wars has been called a "space Western," and has the gunslinging characters to prove it. It's also no secret that he was heavily influenced by the Samurai movie. Specifically the Jedi are where that inspiration is most visible. And if you know anything about film history, you know that both genres heavily influenced each other in a healthy feedback loop. The cowboy is the American samurai, and the samurai is the Japanese cowboy.
Those origins make the title of "cowboy Jedi" such a telling one for what Kanan represents. It's well-known that Rebels, especially at the start, took a lot of inspiration from early concept art for A New Hope- from the design of the Ghost, to Lothal's city, to the Lasat- and Kanan's identity as a "cowboy Jedi" is another facet of that.
It's not hard at all to see where these influences factor in for Kanan. He doesn't need a Filoni-style hat for us to know that he's a cowboy. When we meet Kanan, he's a fairly smooth-talking gunslinger with a heavy disregard for the law. And if you'd like to imagine a horse in place of a speeder when he rides one, you'd find that it can fit surprisingly well.
There are many archetypes of cowboy within the Western, but Kanan would be the good-natured, heroic cowboy over the anti-hero type. While many cowboy heroes that aren't an anti-hero tend to be on the side of the law in their films, Kanan definitely is not- making him more of a Robin Hood-esque cowboy, or the Outlaw Hero. And while Kanan doesn't use his blaster nearly as much in later seasons as he does in the first, he never quite loses that cowboy attitude.
And I think that the samurai connections for Kanan are even more obvious.
The Jedi have always drawn from the samurai (or at least the popular film versions of them), which is why even though the title bestowed on Kanan isn't "cowboy samurai," it also... essentially is. In a lot of ways, the Jedi are Space Samurai, and Kanan is far from an exception. What defines the samurai of the Samurai film is that they are warriors following a strong code of honor- in the case of the Jedi, that means the Jedi Code. Kanan has a fairly loose relationship with strict interpretations of the Code (hi Hera!), making him a bit more of a Rogue Samurai- just like how he also fits into the Outlaw Hero cowboy archetype rather than that of the Marshal.
Something else that identifies Kanan as part of the classic samurai is the focus of his character arc. Kanan's character arc is complex, with many parts concerning his relationship and sense of self, but one aspect of it that gets particular focus is what it means for him to be a Jedi. When we meet Kanan, he's strayed far from the Jedi way, and as he teaches Ezra he rediscovers it for himself, and defines what it means for him to want to be a Jedi, like a samurai picking up the sword again after not fighting for a long time to hold himself to the code he once left behind. And that's still not touching on his blindness being similar to the popular samurai character, Zatoichi the blind swordsman.
So what does it all mean? Why does it matter that Kanan fits into archetypes for these two genres?
While Star Wars was always melded various different influences together, it can usually be a little more clear-cut. In A New Hope, for example, the cowboy influences clearly take the form of Han Solo, while the samurai ones shape Obi-Wan Kenobi. Even though both the Western and Samurai film feed off of each other, the motivations and personalities of their characters differ enough that two vastly different characters encompass those roles. But Kanan is different- Kanan is both of them
Star Wars Rebels, even if people don't always realize it, is the start of a new era in Star Wars. It was the first screen media to be released after Disney acquired Lucasfilm, meaning its job was to give faith for fans who were uncertain about the future of Star Wars (something I personally think it did very well). One of the ways it did that was by pulling on the original sources for Star Wars, rather than simply basing things of Star Wars itself. By doing this, they created Star Wars that was new and exciting, while still feeling like the classic Star Wars that we all know and love. Kanan is the perfect example of a blend of influences, drawing from all of these things.
There's a lot about Kanan that's very special, and that was new and fresh to Star Wars while Rebels was airing. But what I think makes him most compelling is his blend of these two similar yet different archetypes. Wielding both a blaster and a lightsaber make him representative of the best of both worlds- he's got the cool, rogue qualities of the outlaw combined with the strong moral fiber of the samurai. And that's why we all love him so much.