No player but Thiago is truly top 5 in the world in this team. It is all about a functioning system. Yeah yeah you will say van Dijk, who played at second rate clubs until he was 26, Salah, who couldn't make it at Chelsea or Roma, Mane, who scored 21 goals in 67 games for Southampton between ages 24-26, Henderson and Milner who was a joke to everyone before Klopp arrived, and the full backs Arnold and Robertson (at Hull at 23) are all truly inherently world class, but put them in another team and they would all struggle.
This is not about the players, and not even about Klopp being a genious, but mostly about a coherent and sound idea whose time had come, and given the time to be realized. Klopp could've been fired early, most of the players could've just as well been in conference league level clubs at this moment.