We're part of life on Earth. What life on Earth really is, how new species arise, we don't really know. Random mutation and natural selection doesn't explain it, it just restates the problem of what life is at another level of detail. What is really random and where does randomness come from? That's a deep problem for the philosophy of life and existence. If mutations are random how do they end up so often when and where needed and not very often at other times? That's a problem to keep at least geneticists busy for a long time, if the answer doesn't lie somewhere beyond their specialty. How is "natural selection" different from "what survives, survives," a redundancy?
At least we know we're part of life on Earth. We're just like any other land mammal, except for our behavior. We're adapted to the Earth's atmosphere, gravity, Earth foods, Earth bacteria. There are skeletons of presumable human ancestors who lived about any number of years ago you care to name. Not a skeleton for every year, but enough to fill a picture with links including some extra links that probably aren't ancestors. Within the last 12,000 years, the skeletons are supposed to be about the same anywhere as up to 1492. For skeletons that are believed to be about 40,000 years old, the ones in Europe that looked less like ancestors of anyone were called Neanderthal, and the ones that looked a lot like local ancestors were called Cro Magnon. Since that terminology was vague and misleading for human remains outside Europe, finds that would have been called Cro Magnon are now called "anatomically modern humans" as the preferred terminology. If anatomically modern humans weren't our direct ancestors, then who was?
The story scientists are telling now is that about 100,000 years ago, in East Africa some hominids who were already pretty much anatomically modern humans began spreading out over the whole world, and also became human in behavior, at least as far as painting with ocher and making figurines and other things archaeologists can detect that are beyond just making one kind of sharpened stone by habit. But the alternate story that there was some mixing of regional varieties with a spreading group of humans with modern behavior still has some life in it, because science always has new measurements and hypotheses. Maybe there was a bottleneck roughly 100,000 years ago in terms all human ancestors, then those spread out, then roughly 50,000 years ago behaviorly modern humans arose, and spread out and mixed with the earlier wave, but that spreading and genes for intelligence becoming predominant is not yet complete.
Why hominids split from apes and when is a totally separate range of prehistory problem, whatever you believe about the accuracy of various forms of radiological dating. Of course there are still apes, there are still jungles for them to live in and stay safe by climbing trees, where modern humans are in danger from predators because it's harder for us to climb trees, being adapted so well to walking upright since Australopithecines, which they say lived 4 to 6 million years ago. If it weren't for apes, it would be some other distant relative of humans that creationists would ask their question about. Why are there still cows, if humans and cows share a primitive mammalian ancestor? Why are there still flies? Why are there still rocks? If life evolved and humans are the superior product of evolution, then everything in the universe should be humans, nothing else remaining, according to creationist logic.
Now scientists are saying there are a few more million years to wonder about between Australopithecines and a common ancestor of apes and humans. I think that could be the time in which the pre-hominids developed from forest apes to all the adaptations to walking upright that we have. I tend not to believe that random point mutations and selection can explain major changes in species like that, because if you look at the genetic differences between humans and chimpanzees, there are entire chromosome reorganizations. Truly distinct species are unable to produce fertile offspring together, due to chromosome set differences, which implies for every species there was a bottleneck of one lucky complete mutant as the founding mother or father of the whole species, and since it's so hard to breed successfully with chromosome differences, a lucky breeding incident of that mutant and the previous normals, or else parthenogenesis.
As for humans having 26 hour biological clocks, I think the deeper physiological clock of humans that regulates heat has been shown to run at about 24 hours, but the sleep clock runs at about 25 or 26 hours when humans are separated from natural cycles of sunlight and dark. That's a good thing, because it allows rotating your sleep to adjust to the seasons and changes of what parts of the day are good for activities and for sleeping, and it may allow a hunter or scavenger to make use of moonlight, following the almost 25 hour cycle of when the moon is up.
The Garden of Eden is an allegory for something that really happened: Humans started judging what was good to eat for themselves, and invented agriculture, instead of just eating the easy and appetizing fruit and nuts and meat that don't have to be cooked to be edible. That choice condemned their descendants to earning their bread by the sweat of their brows, as it is written.
[I wrote this as a comment to a post at Vault-Co. It stands well enough on its own as a sample of where my thoughts on human evolution are.]