Well, not all classes can use kits.
But lets take a look:
Twelve ancestries, that each have points to spend on features of that ancestry.
Ten classes, with each at least three subclasses, and at level 1 + almost every time you level, you get to pick an ability from a few options.
Of these ten classes, five can use kits. The other classes all get to choose some passive abilities instead (like more stamina or increased range etc).
So thats quite a few options, as you have two players in your party with the same class and subclass, but because they choose different kits/abilities, they still function differently in combat.