I think that it doesn't really matter. Even if you were an alien, it wouldn't make much difference to your life, just like believing you were made by god wouldn't change your life. You're still here and your situation is still the same, no matter how you believe you got here.
It's just something you'd like to believe to make yourself feel more comfortable in a confusing and unsettling world. It doesn't really help you, to think about stuff that can never be proven, it makes more sense to just focus on what you want to do while you're here, instead of focusing on where you might have came from.
Even if you were in an ancient alien's position, or in god's position, and you knew exactly where you came from, you wouldn't sit around thinking "oh, so this is where I came from", you would still just spend your time thinking about what you want to do. The rest of it is kind of a waste of time, and most people who try to spread religions about our origins are just trying to scam you anyway, and act like they know a bunch of secret stuff that you want to know, just so that they can feel important and use their "knowledge" to convince people that they know best about everything, and that you have to do what they say is right.
Nahhh... Just do what you feel like doing, and forget about that stuff. Life means what you make it mean anyway. If you had kids and then a billion years in the future your descendants were living on another planet, wondering where they came from, they would be thinking back to you and imagining how meaningful and important you must be, when you're really just the same as them. The stuff that you do now in your life is just as meaningful as anything that an alien ancestor or a god might have done, so don't worry about what they did back then and just try to enjoy what you're doing now, because it's no less important.
Oh jeez, I'm rambling again.