If alternative is a synonym for real.
Nah but jokes aside, The Roots is one of the best groups ever and Black thought one of the tightest emcees of all times.
As far as "real hiphop" goes, it's one of the weakest defined terms in this genre. Some would call The Roots alternative hiphop or early on Jazz hiphop. Indicating that it's not pure, but what is pure?
If you wanna get into The Roots and you're not used to listening to older hiphop, I would start with Things fall apart, Game Theory, Phrenology, to get warmed up, then Illadelph and Do you want more cause they might be harder to digest.