If your hero section doesn’t make sense, people leave

I built IsMyWebsiteReady to check if a site is “ready”: things like previews, meta tags, favicons, etc.

But now I’m realizing… the most important part is the one thing I don’t check: the hero section.

That first headline. The one-liner.
It’s the part that makes people stay or leave.

And honestly, I don’t know how to help people with it (yet).

So I’m curious:
How do you know if your hero section works?
Do you test it? Ask for feedback? Just trust your gut?