There was a time, when he was taking a break from music, that Justin Timberlake was considered “funny.” This was mostly because of a few appearances on SNL, but enough people, including Timberlake himself, became convinced of it that Timberlake made a brief foray into acting, starring in the consciously raunchy rom-com Friends With Benefits alongside Mila Kunis in 2011.
Timberlake is a decent actor—he was just about perfect in The Social Network—but he was never actually that funny.
That he has more or less returned to music full-time makes more sense, because that is what he is good at.
When he hosted SNL last year, he was legitimately good uncomfortably flirting with Aidy Bryant, and even better impersonating Katt Williams in 2014, with a characterization that should make professional mimicker Jay Pharoah jealous.
When he hosted the ESPYs in 2014, he put more effort into the gig than many hosts, and the result was a show with a level of frisson that exceeded most normal awards shows, let alone ESPN’s made up one.