I hate playing as other characters

[Hasrat]

They always just replace hotbar 1 for me...

That's because most have the setting to replace hotbar 1 with the pet hotbar when the pet hotbar is available. It works similarly to when you need to use a beast tribe mount for one of their quests.

Because the NPCs are mapped to the pet hotbar, probably we'll never see them have more skills than said hotbar can contain.