The Senegalese forward joined for around £34 million in 2016 and there were questions over his consistency at the time, but Klopp says the maturity in his game since then is a natural progression.
Mane has 16 Premier League goals this season and was an integral part of the side which won the title, being many people’s candidate for Player of the Year.
“Maybe people thought ‘I am not sure he is worth it’, but we were 100 per cent sure about him,” Klopp said.
“Consistency was the key and absolutely now what he is doing and how he performs is consistent.
“The level he performs at is unbelievable. He helps us massively. He is a complete player, offensively and defensively he works hard, he is really quick.”
Mane has won four major trophies with the Reds now, while he also shared the Golden Boot last season with team-mate Mohamed Salah and Arsenal’s Pierre-Emerick Aubameyang.
After reaching the Africa Cup of Nations final last year, he was also named the African Footballer of the Year.
Klopp highlighted the importance of Mane’s mentality, as well as his on-the-ball quality, again pointing to his growth as a player as he matured from a young talent.
“We were lucky enough to be around while that [progression] happened, becoming a very good player to a world-class player, no doubt about that, and he is a winner on top of that. It’s great to have him here.”