To say that we live on the only inhabited planet in the entire cosmos is pretty vain, arrogant and egotistical on our part. With all the potential planets that could support life similar to ours it is astronomical odds to bet against Earth being the only planet supporting life forms. The numbers must be in the millions if not billions. This is a topic that many have wanted answers to since the dawn of mankind.
All would be needed is land solid enough to walk on, gills and fins if they are living under water, liquid to drink or oxygen or similar gas to breath. Plus there would have to be sustainable warmth from a sun like star to keep life going. Would a God or Creative Intelligence limit itself to just life on our planet?
Then we can talk about consciousness and how far it can expand. Is the Universe the limit here? I can't see what consciousness wouldn't be able to travel long distances before petering out. How many other sentiment beings are able to pick on it and decipher it correctly?
Radio and TV signals could travel throughout the Universe. But then what would other planetary citizens think of us with what we produce in the way of reality shows, TV wrestling and current celebrities?