You have been asked specifically about Genesis 1:1-2:4 because this story is quite independent of the second creation story that starts in the middle of Genesis 2:4 (2:4b) and continues through to Genesis 2:31. So the first truth you could mention is that there are two creation stories in Genesis, of which this is the first (although written much later than the second).
The chronology is scientifically invalid - for example we now know that the sun and stars existed before the earth and moon, just as we know that the grass and plants could not have existed before the sun.
Hebrew poetry is quite different to Western poetry and relies on repetition of ideas rather that on rhyme and rhythm. The first creation story is poetry.
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If 1 Corinthians 15:1-8 is literally true, then a corollary is that some parts of the gospel accounts are not true. While Paul and the gospels agree that Jesus died for our sins, was buried and rose on the third day, there are also some very fundamental differences. Here, Paul says Jesus appeared to:
. Cephas (Peter)
. The 'twelve'
. 500 Christians all at once
. James
. All the apostles
. Paul
The assumption behind the 'twelve' is that Judas Iscariot was a member of the group and present with them when the risen Jesus appeared. 'All the apostles' appears to be a different group to the 'twelve'. There is no suggestion that the spiritual appearance to Paul was in any way different to Jesus' appearance to those earlier.
A truth that arises from this is that Paul was unaware of much that would subsequently be written about Jesus in the gospels, including the betrayal by Judas Iscariot.