What did I mess up? I'm new and uncertain.

I was installing macOS Sequoia and i kinda messed up and i was getting the 🚫 error with the apple mac startup support page. I accidentally fully deleted everything on the ssd, i managed to get back to where i was at the beginning before all of the OpenCore stuff (techincally im installing high sierra then im going to update back to monterey 12.7.6) but im trying to figure out what i did wrong, did deleting everything delete OpenCore? thats what I assume happened, this is my first time doing this as well so walk me through what i messed up like im five ig.

Author: @Ultimate65