Mane's influence at Liverpool cannot be underestimated, but the arrival of Luis Diaz meant that his position was completely filled if he left Liverpool. With the presence of a potential new player like Luis Diaz, it will certainly be a breath of fresh air for Liverpool's front lines. Although we don't know yet that he will play better than Mane or not, but Klopp was right in signing this player. Because if I see it looks like Mane will really leave Liverpool.
Actually, if you look at the reason behind Diaz's arrival last season, he meant to rotate the players because in the previous few seasons Liverpool lost several players due to injury storms and they couldn't rotate it which made Liverpool not play well and actually if you look at this it is Diaz really went above and beyond and he can do really well there.
As for being a replacement for Mane, even if it was originally like that but in terms of performance maybe it will be a little different but I agree if I say the role of Mane will be filled by Diaz if he really leaves.