Do kittens still see their primary owner as mommy even if the owner is a boy? Yes, is the answer. They see the primary owner as a surrogate mother who in providing food and security keeps their cat in a permanent state of dependent kitten hood.
This state subsists until the adult cat hunts and brings home a mouse. At this point the cat behaves as a mother to their owner and is trying to train their owner how to hunt mice.
It is a rather strange, mixed up or even schizophrenic form of behavior. It seems that the domestic cat is somewhat confused as to their place in human society.
Way back when domestication of the cat started – 10,000 year ago – there was no such confusion regarding the roles of cats and humans.
The cats were semi-domesticated. They lived rather like today’s barn cats. In this arrangement the cat had a friendship with the human but did not regard the human as their mother because the human did not provide in such an intimate way.
It was a looser arrangement and probably a better one for both cat and human. We have gone far away from that initial style of cat domestication and with it brought many failures: feral cats, unwanted cats, declawed cats etc..
In respect of play, adult cats can treat humans as siblings. It is a flexible relationship: the one between domestic cat and human guardian.