Do you think it's possible that an ancient race of alien or people could have existed before the humans that we know of

Yes. There is evidence of an ancient hominid called Denisovans, after the Denisova Cave in Siberia where the remains were found only in the last ten years. They are known almost entirely from DNA that was extracted from several teeth and a finger bone. We know almost nothing about them. Some of their DNA exists today in the DNA from people native to Southeast Asia, Indonesia, and other locations. We know they interbred with both modern humans and neanderthals, but very little else.