Responsive search ads

Hi All.
I am setting up a campaign from fresh.
I am trying “responsive search ads” – some might disagree but I’m giving it a go.
Google asks me to
“Add more headlines View ideas”
– But I’m already upto max number of headlines and used all the google suggestions

“Include popular keywords in your headlines View ideas”
How does Google define “popular” I have looked at keyword suggestors and used what I believe to be popular keywords. I have also used the Google suggestions

“Make your headlines more unique View ideas”
Unique against what? – my other headlines or other people’s headlines or some other metric??
– I have already followed Googles suggestions

“Make your descriptions more unique”
– as above.
SEMrush

Google knows what it wants me to do but doesn’t seem to want to tell me ??

TIA