Am I sure about what?
Please re-read my comment to which you responded and point out where I said anything about variants to come.
"Of course, delta variant was first document before public vaccinations began. And by "all" do you mean all the people in the US, all the people in Mexico, or all the people in the entire world?"
I was responding to your question "But if people all got vaccinated (barring medical conditions that prevents them), would we have this delta variant?" and the answer is obviously yes. Delta was first identified in Oct 2020 before public vaccinations began so clearly vaccinations did not create delta.
Variants of SARS-CoV-2 - Wikipedia
Btw, you didn't answer my question as to what you mean by "all" vaccinated.