Many of the traits that separate Humans from Chimps are traits that are normal to infant chimps but are retained to and through adulthood in humans. Look at a picture of a baby chimp, and note the human looking shape of the head, the erect posture.
In the 1930s there was a movie that had an excentric millionaire seeking eternal life. The missionaire was modeled on JP Getty, complete with a mistress modeled on his mistress.
The scientist engaged to seek eternal life found documents recording an English lord who had not died, though he was over 300 years old. Said English lord had fathered a child when he was 95. Though now a movie would use DNA manipulation, that old movie used some nonsense about carp guts as a dietary key.
So the troika traveled to England to visit the old guy, and found him happily living in the basement of his drafty (draughty, if you please) castle....
...as an adult chimpanzee.
Interestingly dogs have juvenile wolf traits. Perhaps we were chimp pets?