Mac Jones strikes me as a Jared Goff type, in a best case scenario. He can make throws happen when he's in a clean pocket and his first or second read is open. If you need him to extend a play or win you a game himself, you're in trouble. I'm not a big fan of that kind of QB, but they have their purpose. I prefer him to a guy like Trask who fits all of those descriptions only with a weaker arm.
As for Najee Harris, I don't see the point of the Steelers taking a RB in the first round. If I thought this team was close to winning a title and he would put them over the top, sure. But a team with so many holes to fill has no business taking a RB early. I'd go for an O-linemen, CB or, if they really like a guy, a QB, first round. The window for the Big Ben Steelers to win a Super Bowl is over. It's time to prepare for the next era. Taking a RB early is not a good way to do that. By the time the next QB is ready to win, the RB will be a free agent or getting an expensive extension.