Is the Paradox of Value relevant to the value of labour?
Both of these things can be thought of as Supply/Demand problems where the relevant concept is actually how Demand is decided.

First, let’s look at diamonds. Diamonds are of value because people give them as gifts, proposals can hinge on them, etc. Now why that is a question of history or sociology, but the key idea is that people want them and will pay to make sure they can also give them as gifts. It wouldn’t be fun to plan a proposal, get on a knee, and pull out a Ring-Pop..

Diamonds and water are both of high demand! The difference is that supply of diamonds is small, so people will have to compete via price to get their diamond whereas water is relatively abundant. 

Professional sports players too follow this pattern. What’s really important for basketball fans is seeing the absolute best players compete. There’s a reason middle school teams don’t sell out stadiums. So the demand is not for an average basketball player, it’s for the best basketball player. 

The supply of truly spectacular basketball players is small (as the majority of draft busts can show) and therefore their salaries are quite high. Teachers are relatively abundant, so their salaries are a low (tragically so).