Throwing a thing through space at the speed of light makes no practical or even logistical sense, correct, but there's all sorts of weird potential avenues of physics that could be tried, and we obviously don't have a complete or even necessary accurate model of the universe in the first place.

Whatever other intelligent entities here have been here forever anyway. They probably occasionally LARP as aliens, likely as a communicative mockery of the long-term glowie psyop mythologies of gray abductions.