So tell the scientists how to prove that souls exist.
First, there needs to be agreement on what a soul is. There is widespread disagreement about this.
You claim that animals have no souls, but all humans do... even those that are born without a brain. Yet we can tell from the actions of dogs, cats, whales, elephants, and other creatures that they react to stimuli in the same way that humans do.
There is obviously a thought process that takes place in the brains of humans as well as of other animals that does not necessarily have to be immortal or connected with any celestial creatures up there in the sky.
How can you prove that souls are immortal, that animals do not possess souls, or that there is some arrangement that gives the souls of people who have died some form of immortality.
We know that the universe is immense, that entire star systems have come into being, survived for billions of years and then blown up long before our Sun and Earth existed. Nothing in the universe shows any signs of being immortal.