“But God hath chosen the foolish things of the world to confound the wise; and God hath chosen the weak things of the world to confound the things which are mighty;”
-1 Corinthians 1:27
Don't let things that are out of man's comprehension be a "stumbling block" for you. It doesn't matter whether the Earth is billions of years old or thousands. Concentrate on living like Christ by loving others, forgiving them that do you wrong, and spreading the Gospel or "good news".
Look at Proverbs (a book about using wisdom for good in your life) and the subsequent book, Ecclesiastes. The former tells of a life lived in wisdom and it's benefits while the latter, Ecclesiastes (thought to be written from King Solomon's point-of-view, who the wisest and most educated man in the world at the time) comes along and says it's all "hevel" (even wisdom, which is described as what God used to create the world with in Proverbs.)
(Heb. hevel): “futility,” “meaninglessness,” “emptiness,” “breath,” “nothingness,” “absurdity,” and so on. The word means “that which is futile or worthless, of no value or profit,” but it also connotes that which is transitory or passing away. As Solomon observed life, he saw little that exhibited profit and accomplishment. The word all in the expression all is vanity must not be taken to mean everything in the universe for these reasons: (1) The author’s observations are clearly limited to what is “under the sun” or observable. (2) The negative conclusions always grow out of observable phenomena as the expressions “I saw,” “I have seen,” “Again I saw,” and so on, exhibit. (3) “Vanity” is never predicated of God, God’s work, God’s revelation, or man as man. (4) Specific realities are commended by Solomon in such a way as not to be considered vanity (e.g., the fear of God, enjoyment of life, and proper use of wisdom).
Vexation of spirit (v. 14) occurs seven times in the book and contains the idea of fruitlessness or futility. Even Solomon’s wisdom (v. 18) did not suffice to solve life’s ultimate questions. This is the first of several passages in the book that emphasize wisdom’s limitations, whereas Proverbs emphasizes wisdom’s benefits.
Nelson, Thomas. KJV Study Bible, eBook . Thomas Nelson. Kindle Edition.
7:23—8:1. Solomon is known as the wisest man who ever lived, but even his wisdom was insufficient to understand life fully (7:23). In his search for wisdom Solomon found many sinful people (7:26) but few righteous (7:28; cf. Prov. 31:10). In spite of the failures of wisdom, it is still the most attractive virtue since it helps bring inner happiness (8:1).
Here are a couple videos that summarize Ecclesiastes. It's in the "wisdom books" where you'll find the conclusion on how to live life and what to do about trying to answer life's puzzles.