Jango Fett was a known Jedi killer though, which was the reason why he was cloned, so the clones would be effective in killing Jedi in Order 66. He killed half a dozen Jedi whilst he was Mandalore. And he killed that rogue Jedi, Komari Vosa. Even so, he was a better than fully honed Mandalorian.
Jango's only Jedi kill in the movie was Coleman and that isn't really impressive, sure he was a council member but he wasn't a fighter, he was more a diplomat then anything else.
You do have a point though.