I still can't break blocks. I am on Survival and I checked my controls, and my pick block button is button 1. I tried picking dirt but it still won't work.
Setting your button 1 to "pick block" means that your left mouse button no longer does what it's supposed to, which is breaking blocks. Set button 1 to "Attack" in order to use it to break blocks.
Once you've fixed that, go find some dirt and hold down the Attack button (i.e., button 1 a.k.a. your left mouse button) – you'll know it's working because you'll see your arm, tool, or item vigorously smacking at the block, and cracks will spread across the block until it breaks.
"Pick block" means "choose the block", not "pick-axe the block". Block picking to get new blocks only works in Creative mode, and is just a quick way of choosing what block to equip. It has only limited use in Survival since it can't give you blocks, only switch to any matching stack already in your hotbar.