It is worth noting though that as limited as primitive peoples understanding was, almost all of them have some reference to a "creation" and an "end" which when you think about it is parallel to the big bang and the supposed coming collapse of the universe. Science postulated that the universe had always been (with no beginning or end) until Einstein theorized otherwise less than a century ago.
Of course they do. Imagine the caveman on leaving his cave and looking at the animals he has for food and clothing, caves and trees for shelter and fire, water running past in the stream. He has everything he could need. "Who could have designed all of this for us?" he wonders "Well, the only thing I know of capable of that sort of thinking is me and this is all really big so it must have been a big one of me."
This is how it happens because we have evolved to be problem solving animals. We look for problems and find solutions and we are so successful as a species because we do it well. Our caveman was dead wrong though. He is like a puddle wondering who could have made the hole in which he is sitting so perfectly just for him. The hole was there first and the puddle fits it so well because it grew into it. No-one needs to have created it all, it fits us so well because we evolved into it. Darwin killed creationism.
The universe is not thought to be going to collapse into a big crunch. It will go on expanding into heat death we now think.
As to some of their cultural beliefs (i.e. subjugating women, slavery, some others we might consider objectionable today); if there is no higher being of authority then nothing is inherently good or evil. There is only what society excepts or does not except; Those practices are neither good (virtuous) nor evil (sin); they are only what society accepts or rejects and in the end will not matter either way.
It will not matter if we become extinct and take the planet with us since it would only be a coincidence that the universe exists at all.
Exactly, there is no absolute moral authority or good and evil. We are on our own and the sooner we recognise it and agree on a set of morals to live by the sooner we can stop stoning each other to death for inappropriate attire etc. Many say that without the bible there is no morality. We do not take our morality from the bible. We do not stone people or kill our children for talking back as it says we must. We cherry pick the rules we find socially acceptable because we recognise that the bible is not a moral book.