you can do really well in your life as long as you don't think about anything that has ever happened or anything that might ever happen, amirite?

You need your past to learn from your mistakes and experiences.

Example -

Caveman is hungry so he eats berry.
Berry makes caveman very sick.
Caveman is hungry again and sees same berry.
Caveman knows it makes him sick and does not eat that berry.
Caveman eats different berry and does not get sick.
Caveman goes to that berry when hungry now.

so you want humans to devolve, imagination which involves future prediction and past experiences are what distinguish us from animals.

I disagree. Prepare for the worse and hope for the best