For a first character, I'd suggest Rogue.
Max out DEX, but a few points into CON and CHR. Take Deception, Persuasion and Slight of Hand proficiencies and Expertise in Deception and Persuasion.
After level 3, specialize in Thief.
This would be the simplest overall class. No additional resources to manage, you'll be able to do most things you encounter (Opening locks, using dialogue options etc), you just stab people with sharp, pointy objects in combat (Or shoot them with bows/crossbows).
With that, you can get a feel for other classes via companions (Notably, you'll encounter a Cleric, Wizard and Warlock which will allow you to get used to the magic system) whereby you can figure out what other classes you may wish to try in future playthroughs.
