Drivers door will not shut

[lks dcvn]

After reviewing your pix - it looks like you might have too many shims at the B-pillar location (just behind doors), which is driving the top of your door away from the bedside.

Your A-pillar gap (front of the door) in the first picture looks consistent top to bottom, which is what you want to see.

The 3rd picture shows your gap is increasing from bottom to the top of your door, which is not what normally occurs. What normally occurs is the top is removed and the gap at the top becomes smaller as the body folds down due to weight and rust/poor body mounts. This is impacted by shims at body position #2 (the bolts/shims at the front of the cargo floor). Check to see how many shims you have at this position as you may need to remove some/all of them to bring the door back into alignment. Also you may want to see if the bolt is tightened down enough as that would have a similar impact.

Body shims are about 1/8" thick pieces of steel with a hole in them for the body mount bolt to go through. They have them at LMC although you can probably find them cheaper elsewhere.

Link to LMC page for Blazer body mount hardware

Does the passenger side door also have this gap at the top? Any issues with that one closing/opening?