Exactly.
One pays a manager in order for them to try to get the best from a (sometimes) limited squad, people whom you have not recruited yourself, and sometimes, to try to form a coherent team playing style (one that is compatible with the players you have at your disposal) and, perhaps, philosophy.
Additionally, the manager must be able to scout out (or recruit individuals to do this) good options for future purchase (who will fit into what you are trying to do), discreetly get rid of (sell, or encourage to depart), non-performers, or disruptive individuals, manage the expectations of directors, the squad, and fans; manage - with people skills - the team, and the squad, that is, encourage, mentor, steer, advise, - and try not to lose your best players to injury or to other teams, when they come knocking or poaching.
Attempting to argue that because simply Nuno had successfully steered Wolves (with a far better squad) to seventh, that this is a realistic aim, or ambition, or goal, for Forest, is unrealistic, certainly, for a season or two.
It takes both time and money (and no small luck), plus planning, to be able to achieve such an optimistic outcome.