I don't believe in aliens regardless of whatever happens. At least not in the aliens that look and behave identical to us.
Keep in mind that lifeforms need fluids to live (we, earth, water; humans are waterbased). Since there are but a few planets supposedly having water (even less if you look at the quantities) together with atmospherical properties that partially match our own, it is gonna be a longshot to assume there will be aliens that behave like us.
Even if you take another fluid instead of water, you still need some form of atmosphere for it to work. So basically you'd need a planet that has the same rotation and the same distance from their galaxy's heat/light source as earth and its water compared to the sun.
I'd rather call them lifeforms than aliens and they'll be looking alot more like bacteria then quadrupeds or us bipeds.
However, if you'd knew how advanced our technology is in truth, you'll stop believing in stereotypical aliens aswell.
Keep in mind that humans are greedy S's 'o B's who'll do anything to stop better technology from going public if the old technology still brings in the cash. Like medicine; they won't give us something new untill the research and production costs from the old products have been achieved and started to make a big profit and even then they won't give us something new untill the demand for the new product exceeds the demand for the old. one.
Nor do we implement better and efficient fuel as long as there is still gass, oil and coal to be mined.
In short:
Something flew over China, civillians say its aliens, China's government says its a military experiment and you know what, i believe their government for once.