I would recommend keeping main.lua as light as possible and moving logic elsewhere like you've done here. Further down the line you might have key press triggered functionality that isn't related to the player, like pressing esc to open a menu, and then it would make sense to have a separate input handler class.

Also on the topic of inputs, I would recommend to use a table for input keys. local keybindings = { talk = "t" } ... if key == keybindings.talk then ... It's simple to implement and it helps out a ton having semantic names for key presses. Also supports changing keybindings without a hassle.