Williamson won't be LeBron, but sorry, he's a lot better prospect than Randle ever was.
It's not a comparison that's completely off, because yeah, Randle is a very big guy who has good ballhandling skills that are the foundation of his game. The difference, besides the fact that Williamson is way more explosive, is that Williamson can beat guys off the dribble from almost anywhere on the floor. He plays the game like an attacking 2 guard, except he's huge. And because he's so much more explosive, he's much harder to stop around the rim.
Randle at UK was starting drives mostly from 15 feet and in. You couldn't iso him on a defender 25 feet from the basket and expect him to just blow by the guy. You can with Zion, which is where he's most similar to LeBron, though he obviously lacks the all-around skills that LeBron had (though I wouldn't overstate the shooting. LeBron was not, and really still isn't, all that great of a shooter. It's just a question of whether Williamson will be a total 0 with the jumpshot, or hit enough that it has to be respected).