Now, before you get out the stake and firewood to set this heroic ablaze, please hear me out.
Think about Scrum by itself, as if you had never heard of Agile. Scrum is a software development methodology (or framework). Scrum can be implemented strictly, adhering rigidly to the steps and protocols provided by the creators of Scrum. Scrum can be implemented flexibly, where the steps and protocols are viewed as guidelines.
View it as a spectrum with rigid rules on one end and flexible guidelines on the other. It is up to the organization implementing Scrum to determine where along this spectrum they feel they get the best results.
The message of Agile is that any software development methodology will yield better results if that methodology is executed with a specific mindset. This specific mindset is encapsulated within the 4 values and 12 principles of the Agile manifesto. It is also expressed as doing things agilely.
Scrum works best if it is done agilely.
Kanban works best if it is done agilely.
Waterfall works best if it is done agilely but, I would venture to say that no one would call Waterfall an Agile methodology.
Agile is an overlay for all software development processes. That doesn’t mean that the processes themselves are or are not inherently Agile.