I think the best way to tackle this whole conundrum about finding your own meaning is to always be the best version of yourself. You see this kind of talk crop up a lot in eastern stories where the internal battle is about overcoming the self as opposed to fighting the external world at large. While I don't necessarily think I can follow those philosophies fully, because they're extremely idealized and are really hard to honestly achieve due to human emotions, they I do think have given me a nice perspective on how to look at yourself and they are nice ideals to think about.
We have inherent limitations in how much of a mark we can make, especially in this life we live where so many voices drown each other out so individual impact is so hard to make visible. I believe the best way to leave behind a legacy is to always be the best version of yourself and ask yourself what that means. Maybe I will not be as materially successful as my parents due to the changes in the world making such things harder, maybe I will not be immortalized like many famous people and icons in media/history/etc, and maybe my feeble mark on the world will fade like nothing after I die. But I like to believe the people I've met have lived better because of me overall. In some small way I choose to believe my life was an overall positive, and sometimes accepting that is enough for me.
To me if you can help one person improve in life, then your impact on the world at large matters. It is very humble and lacks glamour, but frankly if fame and success involves the type of autistic obsession and other shitshows that get brought out with e-celabs, actually celabs, politicians, or even our own chuubas where people dissect my every word and action to make rrats be it on here, the farms, twitter, or some tabloid garbage, then I'm not sure I want fame anyway. Who cares about 5 minutes of fame if you have to watch your back every single day for clout chasing fuckers trying to get something out of you, the sperg detectives to not take what you say wrong? It just feels like you paint a target on your back for the general public to find a way to tear you down. That type of shit just turns you into someone who isn't you out of necessity, which goes against the idea of being the best version of you, and I'm not sure I'm willing to pay that for material gain.
I like to imagine that I followed my own life and I can say to myself that I lived my life my way, and with that I have lived good enough. Sometimes you have to just accept that good enough is good enough as long as you're being truly honest with yourself. So beyond the question of the what's in the afterlife, then I am content in that outcome. I am me, and that is all I feel I can ask of myself.
Not that I'm trying to dismiss you or tell you that you're wrong for feeling the way you feel. I just think that sometimes you need to look at what you are, what you have, and find contentment in that before you can improve yourself. Constantly making comparisons is just a drag and tends to muddy who you can be, you become a chimera of expectations that you put on yourself. You are not your father, you are you. If you're not doing something horribly wrong, then you should be able to on some level be okay with who you are and what you have.
Here is a song in return.
I hope whatever outcome you come to about your legacy and your life will make you content.