Question: Were Adam and Eve the first cavemen? I don't get what happened with God and the whole prehistoric period. Also, where was the Garden of Eden? Why did they have to leave?
Discussion: Since your last question has specific biblical answers, let's start with why Adam and Eve had to leave the Garden of Eden: Sin brings consequences. Not only does wrongdoing affect the people involved, the cause-and-effect of sin can cause effects for generations to come. So when sin entered the garden, the intimate relationship between God and humankind immediately changed, causing all sorts of disruptions and, likely, making a more discernible distinction between the holy and the unholy. In other words, this perfect place became a holy place where no "unholy" person could live comfortably or at ease. (Dis-ease most likely entered the world then too.)
Besides those biblical concepts, the Bible text itself provides this answer: "And he (God) said: Behold Adam is become as one of us, knowing good and evil: now, therefore, lest perhaps he put forth his hand, and take also of the tree of life, and eat, and live for ever. And the Lord God sent him out of the paradise of pleasure, to till the earth from which he was taken. And he cast out Adam; and placed before the paradise of pleasure Cherubims, and a flaming sword, turning every way, to keep the way of the tree of life" (Genesis 3:22-24, Douay-Rheims.) As Christians, we now know that, in the fullness of time, Jesus Christ became The Way — the Saviour from sin, the Redeemer of God's people, and the Tree of Life through whom we enter into the eternal life our loving God wants us to have.
Regarding the location, no one can be sure where to find the Garden of Eden because the names and even maps of Bible places often differ from those we have today. If you want to investigate the possibilities though, Genesis 2:10-14 offers a starting place for research aided by a Bible atlas, Bible encyclopedia, and/or map of ancient terrains.
As far as Adam and Eve being the first cavemen/women, Genesis places them first in the Garden, then gardening outside that idyllic place with some of their descendants, eventually moving toward a nomadic lifestyle that may or may not have involved caves. That said, Genesis in particular and the Bible in general do not focus on world history but on God's ongoing relationship with us in developing our Judeo-Christian history of faith.
Question: A friend asked me a couple of questions that I could use help answering. The first is asked frequently, I'm sure, and that is …. How did other people come to exist to marry Seth, Cain, etc? The other question is, we talk about God making us in His image and likeness. If God is pure spirit, how can He have an image? I told her that the only way we know God's image is through Jesus, when God took human form. I'm not sure if that is how it is explained by the Church, so I just wanted to get your take on it.
Discussion: Regarding our being made in God's image, I always took that to mean our spiritual selves, for instance, with our God-given capacity for love and forgiveness. In researching your reference to Genesis 1:26 now, though, I see that a footnote in Douay-Rheims adds, "This image of God in man, is not in the body, but in the soul; which is a spiritual substance, endued with understanding and free will. God speaketh here in the plural number to insinuate the plurality of persons in the Deity."
A footnote to that same verse in the New American Bible published on the website of the United States Conference Of Catholic Bishops further explains, "Man is here presented as the climax of God's creative activity; he resembles God primarily because of the dominion God gives him over the rest of creation." To clarify that often-misunderstood concept of dominion, the Catechism of the Catholic Church says, "Each of the various creatures, willed in its own being, reflects in its own way a ray of God's infinite wisdom and goodness. Man must therefore respect the particular goodness of every creature, to avoid any disordered use of things which would be in contempt of the Creator and would bring disastrous consequences for human beings and their environment (339.)
Regarding your question about the existence of other people, Genesis 1:26 records this account of creation: "And God created man to his own image: to the image of God he created him: male and female he created them" (Douay-Rheims.) Then Genesis 2:7 goes on to say how God formed man from the earth and breathed life into him so that "man became a living soul." The Bible doesn't explain beyond this, but to see what the Church says about the origins of people, look in the index of the Catechism for key words, such as "Creation" and "Man," the latter of which yields almost three columns of references. For instance, under the heading of "Man," you'll find the subheading, "resemblance to God," with additional references that bring us back to our origins in God's own image. To see what the Catechism says about that, "Section One: Man's Vocation, Life In The Spirit" offers inspired insights, such as 1702, "The divine image is present in every man. It shines forth in the communion of persons, in the likeness of the union of the divine persons among themselves." Amen.