Mick Jagger can not sing, objectively speaking
If you've ever seen Godard's documentary Sympathy for the Devil (which I do not, not recommend), the early vocal takes are borderline unlistenable. In raw form, Jagger's natural voice is absolutely horrendous. It's only after at least a dozen or so vocal takes that Jagger learns how to strut his stride. You're right, much more of an actor than a singer in any traditional sense.