The US Joint Pub 3-24 stands (shakily) upon this definition of insurgency:

Insurgency uses a mixture of subversion, sabotage,
political, economic, psychological actions, and armed
conflict to achieve its political aims. It is a protracted
politico-military struggle designed to weaken the control
and legitimacy of an established government, a military
occupation government, an interim civil administration, or
a peace process while increasing insurgent control and
legitimacy—the central issues in an insurgency.
The danger of lists: "Insurgency uses a mixture of subversion, sabotage,
political, economic, psychological actions, and armed
conflict to achieve its political aims." Or simply stated, an insurgent acts illegally, and a politician acts legally to achieve their political aims. To employ a list of examples of illegal ways an insurgent might employ puts blinders on the reader, and constraints upon the definition that are both unintended and unnecessary.

"It is a protracted politico-military struggle designed to weaken the control and legitimacy" I believe more accurately is an effort to coerce change in part or whole of a system of governance. It may be protracted, but could be quick. And "control"? This is a favorite word in our foreign interventions in the insurgencies of others because often WE seek control in those places - but we believe that in the US control belongs to the people, not the government. Then there is "legitimacy" - no word is used more often or has more meanings in the COIN business. There is legal legitimacy, a recognition by some formal body of the right of some system of governance to be in power. More importantly for purposes of insurgency, however, is the concept of political or popular legitimacy - the recognition in the population of the right of some system of governance to affect their lives. This is at the core of nearly every resistance and many revolutions. Some distinct segment of the population simply does not recognize the right of the existing regime to be in charge of them. Maybe they were excluded from full participation, or perhaps a foreign power picked the government or has somehow gained a corrosive degree of influence. How matters little, it is the perception that counts and must be understood.

"of an established government, a military occupation government, an interim civil administration, or a peace process"

These are VERY different things. An odd mix of internal and external forms of governance. By dumping all forms of insurgency into this single sack misses important nuances. By dividing by those that are within vs. those that are between one begins to craft a very important sorting out of the nature of things.

"while increasing insurgent control and legitimacy—the central issues in an insurgency"

A bold assumption. Sometimes people just want respect or dignity or justice. We need to be careful not to mirror image our concerns as an intervening power onto the population that is daring to challenge the governance we have so carefully crafted for, or protected from, them.