Sometimes you don't need superstars to shine as a team, just like you said, they have many extremely good players in all roles, that alone is enough to make a team unstoppable. Just have players that are good in their different positions and you're good to go. Last season Al Littihad were so good that they beat both Al Hilal and Al Nassr, infact there was even this very match that Al Nassr were leading with 2 - 0 but at the end, it ended in Al Littihad winning 3 - 2 on the night.
A team without superstars can succeed and win trophies if they have young dedicated players who are willing to represent the team and give their all to ensure they win matches and win trophies but the case of the teams in the Saudi Pro league is different for example Al Littihad that was good last season of you look at the players in the team you will discover that they have young players who have decided to give their best to ensure they win matches for the team.
Al Nassr has superstars like Ronaldo and the rest of the stars last season but coming to this season they have signed more quality players you can't compare their past performance to their present performance the difference is very clear.