After 1.e4 e5 2.Nf3, is 2...Nf6 safer and easier to learn than Nc6? I am an amateur player and do not have much time to study and memorise complicated opening lines. Am wondering after 1.e4 e5 2.Nf3, if 2...Nf6 is a safer and simpler option for black than 2...Nc6. My database shows that after 1.e4 e5 2.Nf3, the move which gives white the lowest winning percentage is 2...Nf6 instead of 2...Nc6.
As an amateur player, you should know the connotation that 2...Nf6  (The Petrov defense) has a reputation of being more boring and more of a draw than 2...Nc6 (leading to the Ruy Lopez, Italian, and Scotch games). However, this really doesn't apply at the amateur level. In fact, you're much more likely to win or lose than draw, unlikely to the masters' database showing that certain lines have a drawish tendency.
So my suggestion, as unexciting as it is, is play what you like! Try out Nf6, try out Nc6, and see what pawn structures/middlegames you're getting in your games. Do you like them? Do you prefer one or the other? Play that one more often!