Aliens have been observing your world since it was first formed from Solar debris. Many of your ancient civilizations have portrayed sightings through their carvings, wall paintings, literature, and folk lore. From the Mayan calendar to the Pyramids of Egypt...Alien influence is evident everywhere on your Earth. On a clear, starry night gaze upon the heavens for awhile and observe the immensity and complexity of the Cosmos. It should not be difficult, even for the most skeptical of Humans, to realize that You are not alone--that there must be other life in this vast Universe. Indeed there is.
Humans have misconceptions of the shapes and sizes of Extraterrestrial Beings. Your scientists seem to have a very narrow focus. They erroneously look for life in Outer Space in similar form and chemical makeup as Humans. Quite frankly, you Humans are very odd looking creatures. I am sure you would say the same for us. My particular "race" (for lack of a better word) has no gender differences. And we have no names. We recognize each other’s genetic code instinctively through telepathic means.
Through a long ago process of natural selection and genetic engineering, my race no longer experiences hate, anger, fear, greed, and most of the other negative emotions that you Earth Dwellers are afflicted with. Therefore, we have no war. It is odd that in Human depictions of outer space (as seen in your science fiction movies and literature), the galaxies are portrayed as being rife with constant battles between the many different interstellar beings. Any civilization that has advanced to the point of inter galactic travel, has long since eliminated such primitive acts of violence and wars.
You might be surprised to know that there are many Alien races that are the size of most of your insects; and there are some that are microscopic (more on that later). You have no idea what a monstrous nightmare your Planet is to the smaller Aliens. There is probably not a more inhospitable Planet for other Alien life forms than your Earth. It is amazing you Humans have survived this long.