These acts are pretty much equal in terms of biological reactions and processes. Your hormones/instincts don't care where you "put your load", they only care th

These acts are pretty much equal in terms of biological reactions and processes. Your hormones/instincts don't care where you "put your load", they only care that you did and normalized hormone levels. It's also not something unique to humans, lots of other animals hump inanimate objects due to reproductive drive/hormonal urges, some primate species are actually quite infamous for their "lewd behavior".