Bible doesnt say but im of the opinion that they were a light brown or oliveish skin color from which both lighter and darker skin shades evolved (Gods evolutiin, not sciences, tho they have basic similarities) through adaptation.
Comparing then to the people groups today, the Bible doesn't say. It's logical to believe that their skin tone was medium brown, because this would have been able to give rise to all shades of skin (what we call black, white, albino, ect.). If what you're indicating, though, is what race they were, then that is easy, there is only one race - the human race. Good observational science has proven this. There are only distinct people groups and cultures, no such thing as different races. If you want a more detailed explanation on how the different people groups arose, then I'll be happy to explain it. Or you could go to Answers in Genesis (www.answersingenesis.org), or The Institute for Creation Research (www.icr.org).
I believe they were the first human beings. I don't believe they are an allegory. They are referred to in other parts of the Bible as actual persons. Maybe tomorrow I'll come back and expound on that further with scripture. It might sound funny, but I do think Eve was take n from Adam's rib. If I revisit this tomorrow I will explain miracles in a way that makes sense. Miracles are something done that seems to defy what humans consider scientific. It is interesting, because I was thinking of submitting two questions on these very subjects. Miracles and if Adam and Eve were an allegory or real. One pertained to infant baptism. Some thing infant baptism is related to original sin, but then believe that Adam and Eve are an allegory and that we came from ape. Somebody I know was saying that they asked a priest (don't get mad at me Catholics) why do you baptise babies? The priest said original sin was the reason. But the priest thought Adam and Eve were an allegory. If they didn't exist there was no original sin. The priest was speechless.
Correctly, WHO were Adam and Eve?, if you believe that they were two human persons, which we Catholics must believe. God made, not created (made from nothing) Adam, the first man, as an adult, out of the dust of the earth. God then made Eve, the first woman, out of some part of Adam's body, as an adult. It says his rib in Genesis. God made Eve because man should not be alone. When Adam first saw her, he exclaimed: This one, at last, is bone of my bone, and flesh of my flesh! (lends credibility to Eve being made from some part of Adam's body, which may nit have been his rib). He said this because he had recently finished naming all of the animals. He called her, woman, which means, (made) out of her man. We have no clue what language Adam, then Eve, spoke. I think it's possible that, before the fall, they communicated with God, and with each other, without speech, even though they were able to speak. Continued in comments.