It's sometimes called a sixth sense, but I think it's true that humans can feel Ki. As for where you feel that ki, I think you can feel it on your skin and in your pineal gland. And I think that reptiles such as snakes have a sensitive sense of feeling that Ki on their skin.
I was walking outside today and saw a snake about 50 meters away. I'm on the leeward side, so I don't think snakes can smell it, and I don't think snakes have good eyesight. Nevertheless, he noticed me, stopped trying to cross the road, and hid in the grass.
And I guess that when people feel Ki on their skin, they actually feel it through their skin and directly in their intestines, and that is what came to be called the tanden under the navel.