Napoli doesn't rely solely on one player, so Lukaku absence won't hinder Napoli from defeating any team. Their players have a built-in mentality to win Serie A. Everyone players will always give their best, and I'm confident that with their current form, Napoli will once again challenge for the title and strive to defend it this season.
Yes, Roma played well against Bologna yesterday, scoring one goal, which is their best result. Bologna is not a small club in Serie A, so at least Roma has shown significant improvement this season.
You are not far from the truth in this case, Napoli for some time now doesn't rely solely on a single player, this is an evidence in the departure of Osimhen who was their main man back and also Kvaratskhelia, many people thought that Napoli will fall for some time but the proved them wrong and without these two main players, they still won the league. So I totally agree with you when you said they don't rely solely on one player.