I know I just frustrate you with this and I'm sorry but I'm going to try and give you a real answer rather than reaffirming that there is no purpose.
What you just described is exactly why people say it's about the journey not the destination.
These past two weeks have been fucking hell for me, but I know it won't always be this bad. I'll interact with interesting people, meet new ones, be intimate, experience art and beauty, create (even knowing the creation won't last past my life, like a sandcastle), lose, suffer, and triumph. At the end of my life, it all is wiped away by death, as you say (minus the rippling effects I had on those around me, but it won't matter to me once I'm dead bc I won't exist for it to matter.) However, it will be MY life. They'll be my stories and interactions. I'm building the coolest sandcastle I can even knowing the tide will knock it down. I want to remember getting in a wreck yesterday just to get home for my AC to be broken; trying to be your friend and observing your search for answers; dating my first girlfriend where it didn't work out; getting fired; wandering the streets thinking about how small I am in the universe; hating wage slavery and fighting for a way to have more freedom; and everything else in between until I die, because the sum of those experiences comprise my life and for this one tiny brief moment in the universe it is something that is mine and no one else's.