What makes a temple a sacred place?
You do.
It's you who considers a place sacred and communicates it through your actions and treatment of. When I treat my puppy as a sacred being, they are. When you treat your home as a sacred place, it is.
Because we want high quality divine output here, this temple is a sacred place. It is possible to have everywhere one is be a sacred place. It is possible to close your eyes, listen to music, and be in a sacred place; wherever you are.
Humans are often tainted by distant forces so this is about other beings... but when you make certain a sacred stream in your forest is the sacred stream, the birds will interact with it similarly, as will the other local beings. They will be respectful of the beautiful stone paths you make and what you weave in to the trees. They have no media corrupting them. Sometimes they see the emotional irreverence of distant humans; and that just makes them value your sacred stream the more. They are here and now and, for them, the world is a very small place, with you and the sacred stream a very powerful part of it. When you show, through your treatment that you are interacting with somethingsomewhere sacred, there need be no words. this communication trandscends species. Remember when birds leave shiny things in your path: you are making the sacred place for all of you.
So, is there possibility of including humans in a sacred place? Yes. But, for all but the most enlightened humans, it must be specifically delineated as 'Sacred'. Hence a Temple. Hence a Temple being sacred.