I would say out of Engineer, Agent, Burecaurcat, or an Adventurer any except Agent will be fine.
Adv would be a good choice because they can use 1he or pistol and have heals.
Engineer to me feels weak at low level as a new player. Eng uses Pistol
Bureaucrat same as engineer but I feel it has better survivability as new player because you can put things to sleep or take them as a pet for extra damage… I found Crat more fun than Engineer but a lot of people seem to like engineer at later levels. Crat also uses Pistol.
Agent is ok but there is more to learn and deal with because Agent uses False Professions aka FP and it lowers your stats… most of the time you might play as FP Meta-Physicist (MP) or Soldier or something because casting things cost extra nano and skills when you are a false profession and some professions are easier at low levels to use in False Profession
I’d hold off on agent until you have learned more about the game.