It wasn't tell after I watched The Mandalorian that I realized that Jango Fett is a Mandalorian. I then began to remember the scene were Obi Wan travels to Kamino to question Jango. When they finally do meet for the first time Jango doesn't have his helmet on.

According to The Mandalorian, that is clear violation of their people's code. I've had a few theories on why this wasn't a big deal in the prequels, but I mainly think it was because the Mandalorian "Can't show your face" rule hadn't been implemented into the story yet. I honesty have no clue and would appreciate an answer.

Edit: I now understand that Jango wasn't a Mandalorian, he just wore their armor. Thanks to everyone who cleared things up for me.