Actually the most likely explanation is that we were engineered. There is genetic evidence of such, ie, the HAR (HUMAN ACCELERATED REGIONS) regions of our genome.
https://en.wikipedia.org/wiki/Human_accelerated_regions
A number of these regions are specific to effecting the development of certain parts of our brain in the womb. I don't recall the specifics off the top of my head, but the genetic/evolutionary mathematics do not add up by following the typical mutational change from ourselves, to apes, and the previous ancestors. Genetic Mutations can often be tracked and anticipated over millions of years by comparing the genetic differences between various species, yet, there seems to be a huge jump/change when it comes to apes->humans, hence these regions being called "Human Accelerated Regions"
These regions have often been used as a topic of religion argument and "proof of god" / intelligent design. To my knowledge there is no known explanation for these regions, but given the known existence of aliens and the stories of us being created "in gods image" and such, then occams razor would dictate that we are the result of genetic engineering.
If I'm not mistaken, the story about the Sumerian God Enki genetically engineering humans from his own DNA and Ape DNA, predates the discovery of the HAR genes.