All characters are just types of 'adventurer'. It's just about how much you want to subdivide it. Clerics are a type of wizard, right? Just with different spells. Rangers are fighter/rogues with some nature skills. Barbarians are just angry fighters. Everybody's just an archetype of 'adventurer'.
Or maybe just two classes--"Fighty" and "Magicky". You can make a ranger or a druid or a paladin out of those with the right multiclassing and skill choices. A rogue is Fighty but has lots of skills. A druid is Magicky but their spells are all about trees. Your paladin is a Fighty/Magicky multi class with Religion proficiency. How simple do you want to go, or how detailed?
I lean the other way. Take a concept and give it the full deluxe treatment you can only get from a class. Have a thousand classes, all given loving detail. A class too niche for your tastes? Don't use it. I'd be happy with a Rat Catcher class and a Musketeer class, each with unique features, treated in-depth. Every class a joy to discover and play. Some will get used more than others, sure, but each is unique.
But it's all down to taste. Boil every concept all down into bland variations of a handful of classes or go into excruciating detail on each, or anything in-between. Count me in for a thousand classes! But there's no wrong answer here. It's really just a question of taste.
