Greystoke: The Legend of Tarzan, Lord of the Apes 1984

A shipping disaster in the nineteenth century has stranded a man and woman in the wilds of Africa. The lady is pregnant, and gives birth to a son in their tree house. The mother dies soon afterwards. An ape enters the house and kills the father, and a female ape takes the tiny boy as a replacement for her own dead infant, and raises him as her son. Twenty years later, Captaine Phillippe D’Arnot discovers the man who thinks he is an ape. Evidence in the tree house leads him to believe that he is the direct descendant of the Earl of Greystoke, and thus takes it upon himself to return the man to civilization.