Well, that is indeed the question.
This is the area of Hermeneutics. It’s complicated 
So, let’s not get into Text Criticism and establishing the text, and the translation process, etc., etc. Let’s skip a number of very important steps and arrive at an agreed upon text and a translation that is trustworthy. Then, how you approach the Scriptures will greatly impact what you get out of them. If you think they are a bunch of man made stories - then you will get something different out of them than if you approach them with a different set of presuppositions. If you approach them as the Word of God given to men - then you will get something else out of them. How do you know which set of presuppositions are the right ones with which to approach Scripture? It comes down to what you say about Jesus. The One resurrected from the dead points to the Scriptures as trustworthy. I take His Word for it because I am convinced by the evidence of the Gospels and the claims in 1 Cor. 15 that He did rise from the dead. So, I approach the Scriptures as the Word of God. That influences what I get out of them.
What do the words mean? How do you determine the meaning of the words? This is where the difficulty of dealing with ancient texts come in. To understand what is being said one has to know culture and context of the original writers and hearers. In the context of the issue of science and the bible I think John Walton and Denis Lamoureux do a good job of explaining this and showing this. If you read into the text your own culture’s presuppositions and worldview you will get an inaccurate reading.
So, you keep your knowledge of ANE culture and context in mind as you read the text and arrive at some understanding of what you think the text means. How do you know you’re right? It seems there needs to be an appeal to an outside authority…
So, either you make yourself the authority and say - this is what it means because this is what I think it means… or…you appeal to another authority (i.e. teaching magisterium in the Roman Catholic Church, etc). This is the problem the Church of Rome brought up to the Lutherans (I’m one) during the time of the Reformation. It’s a valid concern. Rome points to a Teaching Magistrerium that they believe is directed by God - so any biblical interpretation must fall within the acceptable parameters as set by the teaching magisterium. Lutherans and the protestants objected to that and pointed to Scripture alone as the source of authority - not Popes and Councils, etc. However, that still leaves the question of authority unaddressed (a troubling issue for us Lutherans and should be for all protestants).
However, it seems to me that modern day Protestantism (of which I do not count Lutherans a part) has made the individual the source of authority. Me and my bible and my interpretation is as valid as any other. Radical individualism, somewhat aided and abetted by radical post-modernism, has led to a continual fracturing of the Church…everything is subjective and truth cannot be known - so I make myself the sole authority.
As a Lutheran I attempt to have my cake and eat it to. I do not believe that there is a divinely inspired Teaching Magisterium that serves as the source of authority in biblical interpretation. However, if my interpretation is something that has never been taught in the 2000 year history of the Church - then either I am a genius or a heretic. Odds are the latter. So, I am very uncomfortable with innovations in the Church and generally seek to find myself in the line of the 2000 years of the Church. In fact, that was the argument of the 16th Century Reformation Lutherans - we’re not saying anything new here - it is the Roman Catholic church that has introduced teaching out of line with the historic Christian Faith.
With regard to the issue of science and the Scriptures - there has been no strong consensus in the history of the Church on how to understand Gen 1-3, for example. In fact, it could be argued that the more fundamentalist approach to Gen 1-3 is out of line with the majority of the 2000 years of the Church. So, using reason (fallen as it is) and the Church that has gone before me as a guide - I try to steer clear of heresy…and settle on the correct interpretation/exegesis.
So, as the professor who taught me hermeneutics at seminary was heard often saying to us: “What do we know for sure?” What is it that we can safely say, with almost universal agreement, is true from the Scriptures? Establish these things (I’d argue the historic Creeds of the Church do a pretty good job as a start, but there is a lot more). Then we need to do the difficult work of wrestling with the texts that seem difficult to understand or which have not had a consensus through the history of the Church - and come to conclusions based upon our best attempts at faithful exegesis in conversation with those who have gone before us as well as those who are with us now - though conclusions that are perhaps not as certainly held as the universally held beliefs of the Church for 2000 years. I’d suggest that the question of “Adam” may fall into that category.
