Mind is perception of the reality we are immersed within and it requires a brain for that condition to come into being. It requires also a self-reflective brain which is only available to a few higher animals viewing themselves in a mirror, but it is unlikely that any animal other than human speculates beyond realizing the image is them, that they have a perceiving mind. Probably anatomically modern humans before 100,000 years ago, those who lacked syntactical language, would carry the concept of mind beyond observing the events before them. It wasn’t until after about 40,000 years ago that modern humans clearly leave evidence that they had abstract thought. They needed syntactical language before they could develop much if any concept of past or future. Today was the limit of time and the limit of mind.
The concept of soul existing beyond today and on into eternity requires a language that can project happenings into the future and recognize a sequence of events in the past, and see abstract causes and effects from various previously random happenings. Mind is instantaneous and dependent on short-term memory, and events of medium-term memory of a given day, or sleep cycle. Soul is a projection available to the mind for explaining to itself the happenings outside of the world of today. Once that is within the experience of a mind it can make the next step of projecting the mind, now renamed the soul, into the indefinite future and past and distant places. With that option available the soul can inhabit the minds of remote people and creatures and become eternal. All of this is a projection available to the mind once it develops its language to the sophistication where these options are available.
It seems reasonable to ask our linguistic community to explore new methods for expanding our language to access new forms of reality.