We are no less significant than any thing else in existence, other than we have a greater level of consciousness than that which we see around us. This is not to say that there are not others elsewhere who have achieved far greater development in this regard than our species.
There is no such thing as a personal God. As you point out,
"This God knows and loves each and every one of these primates individually and knows when they have prayed or not."
Existence is ruled by universal or natural law - cause and effect. These laws are unchanging and cannot be broken.
One of these laws relates to Intention and this is why prayer does work, especially when done as a group. Numbers and emotion do count.
