I am a Christian. I am not what someone would call a creationist.
The only "theory" of Bible interpretation of these matters that I have ever found to make sense is the worldview theory.
Basically, people that wrote the Bible did not know or care about science (since it did not actually exist at the time) and the Bible was written from that point of view. There is no science to be found in the Bible. There is, however history- but once again, it is written using the language and worldview of ancient peoples, which is quite different from ours.
There are many things in the Bible that are baffling to us (such as the days of creation) that would make perfect sense to the intended audience of these books.
Because, in fact, these books were not written with us as the intended audience.
If you are interested, Carol Hill wrote a book about these issues which is quite illuminating.
https://www.goodreads.com/book/show/46043079-a-worldview-approach-to-science-and-scriptureI will say that, despite the fact that I am an evolutionist, I do think the young earth creationists are probably close to being correct about the their dating of Adam in the book of Genesis... the story of Adam and Eve starts to make sense once you realize that it is the story of the beginnings of human civilization in Mesopotamia (the end of the stone age, and the beginning of the bronze age, with the creation of agriculture, herding and metal working) rather than the story of the first humans on earth.