I used to be a staunch believer in the literal reading of Genesis creation account. But I have since read various books on the matter, some from young-earth Christian writers, and others from old-earth Christian writers. I am now convinced that the young-earth version is just wishful thinking and just does not stack up. There are so many geological records that prove the earth cannot be a mere 6000 yrs old. And I have come to terms with that from a Christian perspective as well.
To me, the bible must be absolutely true. Full stop. But a lot of our understanding is of our own interpretation, not God's. For centuries we have got it wrong in many ways, and over the years we have made discoveries and adjusted our thinking to align with that. Take the views of the Pharisees as an example - we can see where some of their ideas are just nonsensical, but with the knowledge they had at the time, you could hardly blame them for their mistakes. Same today, we KNOW things now that has changed our interpretation. Eg, scientist claiming a helio-centric cosmos were burned at the stake, but now you'd be a nut to say the earth was the centre of the universe.
So my view, is that science is probably right most of the time; I used to think there was a lot of anti-religious conspiracy going on, but now I accept that the scientists really do work hard to draw accurate conclusions on hard facts and mostly disregard unproven ideas. But I also believe the bible MUST be true. The problem I think is that scientists use their 'knowledge' to laugh at Christians who refute them with no basis; and likewise the Christian don't like what scientists claim, so put up walls to say they are deluded. I truly believe the TRUTH (once known) will satisfy BOTH parties.
So with Genesis, sure - I totally think the creation account, while TRUE, is a simplified version for our understanding. Being mindful that the bible is not a book of scientific revelation, it is a book primarily about the redemption of the corrupted heavens and earth (yes, heaven too).
So, billions of years from the beginning to Adam and Eve - for sure.
The age of first man as 50,000 years ago? I really couldn't say - but if it was, it wouldn't ruin the bible for me. (God never said the earth was 6000 yrs old, that is man doing some sums from various scriptures. But there are possible gaps in the record, and there is precedent for that, i think with Mary's genealogy, some generations are skipped, for example.
Evolution of plants and animals? This was a hard one for me, but I am now convinced that evolution is a fact. The geological record is a history book of the earth, it wasn't created by God to trick scientists. But hey, even with all that, it is still God's creation - so where's the problem. Scientist go on about the big bang - but what caused it? Its still just a theory of course, but even so, why can't a big bang be God's work?
(..and with all that said, I am always open to changing my mind given worthy evidence/reasoning.)