It was, I assure you it was. The most professional army at the time in fact. Formed by the veteran triari, the experienced princeps, and then the new soldiers, unexperienced velites. 2000 soldiers forming one legion. Two of them to be commanded by a consul. Two of them elected each year, since the beginnings of the Republic (year 500 something, which is quite early).
Also, a legionarie is not a superman or ultra soldier, it's the name given to a component of the Roman Legions. A soldier from 600 BC was a legionarie, and one from 200 AD was too. Legionarie comes from term legions, and legions existed far earlier than 200 BC. With time, what was changed, was the structure of legions (ex: 2000 men to 5000 in Battle of Cannae and stuff like that), or the equipment, but the soldiers were the same