I’m certain you know your startup inside and out (or at least claim to), but you’re not your end-user, and they don’t understand it so easily (or claim to).
Your audience may be executives, developers, Millenials, Boomers, or whatever, and they understand their industry, but it doesn’t mean they understand your solution.
It is your job to explain it to them, and a straightforward way is to approach it as if you’re a beginner.
Just like going through the Mommy test, take a look at your message or copy from the eyes of a beginner.
At any time, if you need to add more details, dig further, or even complicate it for one reason or another…it would be easy for YOU to do so.
…but to quickly simplify the complex, that won’t be easy without preparation, and your beginner may lose their patience beforehand.