Placing Blocks/Mining them or attacking certain mobs, No effect.

I had just updated the game and started a new world, But when I tried to break the wood to pick it up, it had no effect, so I tried in creative mode to place a block and I could not. I tried changing the settings to see if I could get it to work but it still did nothing. The only thing the arm can affect is the villagers and animals, I can't attack Hostile mobs.