Lewandowski is a sniper and the number of good snipers isn't that big in the football world. In each league you barely find a couple. Their performance depends a lot from their teammates assists. Benzema shined once CR7 were out of Real Madrid. Mbappe has extra skills, and definitely Lewandowski doesn't miss once he gets a good opportunity. I don't think he is overrated but don't expect a lot of him if his teammates aren't doing good.
Robert Lewandowski is a player who has above average skills, his calm nature on the field always allows him to score goals and of course he is the best executor because he can take advantage of the ball from the back team who always gives full support and hopes to get a lot of goals.