Could the scriptures from 2000 years ago been written in a way so they at that time could understand the more simplified verson?
It could also be that God is behind how evolution actually works ( creation hidden within evolution)
I personally don't buy that explanation, that people were to "stupid" to understand it. Because the bible is not a scientific book, so it could simply have said
"I, God created all life" and just keep it with that. It would have been an even more simple explanation and would not conflict with evolution. And besides that, it is not even be a simplified version, it's straight up wrong according to how we know it works.
There are people that will say that God is behind evolution and he put it all in motion. Again, if I were a believer I wouldn't go with that, because it seems to simply be a way to dodge the issue and still it is not what the bible say. You would be reading stuff into it, that is simply not there. But a lot of people see it like that and make it work for them.
But for me, I would stick to the idea that Genesis is not to be taken literally, but as a poetic description of how God is said to have created everything. And whether he used evolution or not doesn't really matter, because its not really the purpose of Genesis of trying to give a scientific explanation of creation. But rather to explain humans, animals, our existence and relationship to God. But this would be a "modern" day understanding of it. But I would think that back then they believed that it was how it happened and it was understood literally as the way God did it or at least as the best explanation for it.
The reason for that is that I think it makes sense if you don't have the knowledge that we have today, and just had to make a qualified guess of how all of this started based on what you observed around you. Then it is not a bad or poor guess that they made by any means.