By races I mean entirely different races such as giants, dwaves elves, ect. Do you think any races, be it alien or indigenous actually interacted with humans?
..."races"? Giants, Dwarves, and Elves in Lore aren't different "races"; they're different types of wights.
In mythology I don't see it as fiction but legend and there is always some truth to legends. Otherwise they wouldn't be legendary in the first place. Perhaps beings from outer space or another dimension, like the Annunaki or other gods came and other races interacted with humans or even interbred with them. Some might be extinct but perhaps some still do exist and are in hiding. After all we haven't explored every square inch of Earth? How do we know there's no intelligent race living in the depths of the cold arctic or underwater or underground in the mountains?
Well, if that's really what you're after... they did exist. Once. Long ago. But as far as we can tell, they're all gone. We're the last.
Some small parts of them still exist in some of us, sure. But it's not enough for meaningful distinctions to be made.
BTW, they were just as biological as us. They didn't come from another dimension, or another planet, or deep inside Earth, or the Poles.