Why do I have so much stuff? I hate it all. Should I give it all away? Ugh or set it on fire (probably not very eco-friendly but very emotionally satisfying)
What shit is worth holding onto? (This seems like it might be a pretty deep question. Discuss.)
I will refer you to this comment I made a very long time ago but TLDR: I fucking love my stuff.
I can't offer any meaningful advice that isn't already in this thread in the event that you do get rid of your stuff. Keep the important things.
In my circles, I always see stories of grandparents/fathers/mothers/etc leaving something behind of a common interest that sorta carries the story of lost relatives down to newer generations.
Old guitars, tools, a classic car half way through restoration, etc. These items bring together generations in a way that ties these people and their stories together, similar to the immortality thing you mentioned.
As a kid I had to clean out my great grandmother's house after she died. It was a whole summers worth of work but me and my grandpa worked through it. I got to learn about the Brooklyn neighborhood he grew up in. I got to learn through items more about my great grandfather I never met, about my great grandmother who I mostly knew through dark basement apartment visits. I still use my great grandfather's oil stone to sharpen knives. Something about that intergenerational connection is important to me.
Aside from small items here or there, I generally don't have many other "artifacts" that connect me to older generations that I can actually use and live through. So now in my day to day life, when I buy things, I consider if this is something i'd like to leave behind. Things I wouldn't care about leaving behind I'm far less attached to, but I'd like to retain items that I may forget about, but my children and grandchildren can learn more about me through.