Just heard 2 shiurim last night before selichos by R Shafier (TorahAnytime) that deals with this question.
The world could have been created with maamad Har Sinai with all of us there.
Yet the Torah shows how Hashem prepared the ENTIRE world for just ONE person, Adam.
This teaches us the principle of that the world was created for ME.
He then continued that in the Next World, we remain the same character that we’ve become in THIS world.
So that using TIME, a most precious commodity, we must have goals and accomplishments and become the person we wish to be…