Humanity's biggest problem is that we believe that if we haven't achieved something then no one else has, but this is simple not true. We have to remember that at one point the advance ment of science was held back in the dark ages and remember that we are earth's second children. There are probably several alien civilizations out there amongst the stars who are far more advanced then use who never went through the dark ages and have been around since the dinosaurs but never had the whole asteroid event.
As for those who might say "well why haven't they contacted us yet?" Well you have to remember that it's a big Galaxy out there and our solar system is one grain of sand in a rather large beach. They may simply have yet to come across use Or may be aware of use but refuse to contact humanity as of yet because they may see use as not yet ready to join what galactic community that might be out there. As we are rather divided like broken glass and in order to achieve interstellar travel we must put aside our differences and come together.
Food for thought.