Minecraft – When I try to break a block it opens the game menu

1. Hit esc to go to the options menu

2. Click Controls

3. Set the key for 'Button 1' to left click, and set the key for 'Inventory' to e.

It's highly recommended to stick to the defaults.

To my knowledge, baby zombies can't break doors at all. I just tested having one aggro a villager through a wooden door, and the baby zombie did not break the door.

If you'd like to test it yourself, go into creative and test it using ' /summon Zombie ~ ~ ~ {IsBaby:1} ' (The ~'s denote your current x,y, and z coordinates). Put him outside an enclosed building with a door, that has a villager in it.