Cool. Sometimes people use “meta-narrative” for that kind of thing if I am understanding your point correctly. Like the overarching message-focused story of an organization. But, sure, use narrative, as long as people understand what you mean, all cool.
Yeah, your observation is on point—most of the time people (audiences) do not actually “track” about an organization. But that doesn’t mean it does not matter—on the contrary. The narrative is generally absorbed subconsciously, by being exposed to multiple stories from the organization.
I’d say the mission statement is something else than the narrative and more of a part of the strategic-domain than communications-domain. But definitely, the mission informs communications.
On your last point, I’d not say “less coherent” but maybe “vaguer”. If you are trying to control a narrative, I wouldn’t say it is not coherent. It is hard to control, yes. But I am not sure if it lacks coherency. But I think, both strategy and narrative are hard to understand when you are looking outside-in but feels more coherent from inside-out.
I also have suffered from this (and still do, really). I will share some lessons that I have picked along the way, followed by a couple of book recommendations.
The lessons:
Focus: Most of the time the issue is you are trying to communicate way too many things. Now I try to contain my message to one single point. This helped me immensely.
Message House: A framework in branding and PR, I advise you to do a quick web search on this. With my previous bullet, I “construct” my message house with these components whenever possible: (1) Anecdote, preferably a personal one. Kicking it with a very short story that is central to your idea helps capture people’s attention immediately; (2) why this matters, why I am telling you about this; (3) Sizzle, or a very quotable quote. If people wanted to tweet one sentence from your “speech” this is it; (4) Data point or one last anecdote to enforce the central theme.
Fluency: You might know what you are talking about, but if you are not fluent about it, it takes a lot of time to put stuff together, and it feels like you don’t know what you are talking about from the outside. To overcome this, you can drill things down. Anecdotes or data points you occasionally use; you can create word blocks of your world view that signals where you are looking at things from; you can have identity related short blocks and exercise on them constantly to get yourself fluent on very specific little blocks, which then you can use as springboards or solid middle- or end-points in your speech.
Book recommendations:
Smart Brevity by Jim VandeHei, Mike Allen, and Roy Schwartz
You’ve Got 8 Seconds by Paul Hellman