As you know, I don’t believe death preceded the Fall of Adam and Eve, so I don’t believe that mankind gradually arose through the mechanism of “survival of the fittest.”
And regarding the apparent old age of the universe, let me quote Dr. Danny R. Faulkner (MS Physics, Clemson University; MA, PhD Astronomy, Indiana University; and he then taught at the University of South Carolina for 26 years), from his article, “Seeing Stars in a Young Universe”:
We need to recognize that God used many processes during Creation Week that are different from processes today. He didn’t make Adam instantaneously out of nothing, but instead formed him from the dust of the ground (Genesis 2:7). God used a similar process to make the land and flying animals (Genesis 2:19). And he caused the plants to grow rapidly out of the ground on Day Three (Genesis 1:11–12). In other words, God rapidly and miraculously matured many things during Creation Week. It seems both logical and theologically consistent that, in a similar manner, God could have rapidly “matured” the universe, bringing the light from distant objects to the earth in a way similar to trees instantly sprouting and rising to full height.
In addition to creating the physical universe during Creation Week, God also created the laws that govern it. What if these laws were not in full effect until the end of that week, as we see when God created mature plants, land animals, and the first two humans?
Instead of bringing starlight to earth according to physical laws, God could have miraculously solved the light travel time problem on Day Four, before putting the laws that govern light travel into effect. After all, nearly everything about creation was miraculous.
I still think that everything that was made–that is, everything that is not God, e.g., angels, men, galaxies, animals–was made during the first Six Days of Creation Week.
Also, I believe that the first six days of Creation Week quite possibly prophetically anticipate six millennia from Creation to Second Coming, with the seventh day/millennium being the Messianic age of peace,
2 Peter 3:8
But do not forget this one thing, dear friends: With the Lord a day is like a thousand years, and a thousand years are like a day.
This idea is called the “Millennial day theory”:
The Millennial day theory, or the Sabbath millennium theory, is a theory in Christian eschatology in which the Second Coming of Christ will occur 6,000 years after the creation of mankind, followed by 1,000 years of peace and harmony.…The view takes the stance that each millennium is actually a day according to God (as found in Psalm 90:4 and 2 Peter 3:8), and that eventually at the end of the 6,000 years since the creation, Jesus will return. It teaches that the 7th millennium is actually called the Sabbath Millennium, in which Jesus will ultimately set up his perfect kingdom and allow his followers to rest. The Sabbath Millennium is believed to be synonymous with the Millennial Reign of Christ that is found in Revelation 20:1-6.
Many Jews similarly believe the Millennial day theory:
According to classical Jewish sources, the Hebrew year 6000 (from sunset of 29 September 2239 until nightfall of 16 September 2240 on the Gregorian calendar) marks the latest time for the initiation of the Messianic Age. The Talmud,[4] Midrash, and the Kabbalistic work, the Zohar, state that the ‘deadline’ by which the Messiah must appear is 6,000 years from creation. According to tradition, the Hebrew calendar started at the time of Creation, placed at 3761 BCE. The current (2019/2020) Hebrew year is 5780.
The belief that the seventh millennium will correspond to the Messianic Age is founded upon a universalized application of the concept of Shabbat—the 7th day of the week—the sanctified ‘day of rest’.
Of course, there is certainly disagreement among young earth creationists (whether Christian or Jew) about the date of the Creation of the world; for example,
-The Byzantine calendar: 1 September 5509 BC
-The Hebrew calendar: 6 October 3761 BC
-Archbishop James Ussher: 22 October 4004 BC