Easiest character to get into the game is Soldier 76. His controls are basically every FPS character, so it'll help you get the pacing and feel of the game.
After that, experiment with everyone. A good rule of thumb is to learn one of every class of characters in case your main gets chosen before you lol.
As always (and I tell every new player this), if you hear angry Japanese, run away. You'll know what I mean.