There is no rhyme or reason that we are here. We are bacteria growing on a ball of dirt in space. there is no big thing that anyone finds to hold them here. Hell, most people feel exactly the way you do but they never admit it.
That's not to say there's no reason for it. you've been given a gift. The line of your ancestors almost dying, meeting, fucking, fighting, and conceiving life has finally lead to you.
Don't let that fill you with a sense of letting those people down. you've been given a gift.
You don't feel bad when people give you shit for a special occasion, right? This is exactly the same. you didn't ask for this. appreciate it and savor every god damn second.