Isekai is a genre where every little gimmick from a work that gets a bit popular immediately becomes a micro-trend. The main character is an old guy! And he reincarnates into some weird thing that might not even be a life form! And he has cheat skills! And he got kicked out of the hero’s party! And he’s a villainess!

So a lot of works would have to be considered blueprints by that standard, I think.