What is a soul?

"They ask you ˹O Prophet˺ about the spirit. Say, “Its nature is known only to my Lord, and you ˹O humanity˺ have been given but little knowledge.” '(85) Al-Israa - Holy Quran.

A non-existent thing that people inferred had to exist in order for us to survive after our brains shut down (and to have existed prior to being born).

Just one more vague, warm & fuzzy, non-explainable, term for a non-existent thing that has a definition that depends on the person using the term and on the circumstances in which they're using it. Kinda like "spirit".

A soul is a mythical thing that has NEVER been proven to exist by anyone.

Our spirit and physical body combined is the soul. Death is simply the separation of the spirit from the physical body. The physical body is made from the dust, or elements of the earth, whereas the spirit comes from God.

Often the soul is equated with the total person. For instance, Genesis 2:7 tates: “God proceeded to form the man out of dust from the ground and to blow into his nostrils the breath of life, and the man came to be a living soul.” The first man, Adam, was a soul.

The understanding that the word soul can mean the whole person is supported by other scriptures. For example, the Bible speaks of a soul’s doing work. Leviticus 23:30 The soul is spoken of as being impatient, irritated, sleepless, fearful, and depressed. Judges 16:16

 Referring to a soul as a person, Romans 13:1 states: Let every soul be in subjection to the superior authorities.” And at 1 Peter 3:20, we read: “In Noah’s days, a few people, that is, eight souls, were carried safely through the water.”

 Nothing in these scriptures indicates that the soul is some immaterial entity that lives on after death.

Therefore, all living creatures are souls.  

It is kind of mythical thing that may or may not be real that supports any living creature.
In my way if feel all of religion is not realistic as Science says all living beings survive as they breathe Oxygen

 a type of music of course

When God created man HE breathe into man's nostrils HIS spirit  which cannot die.  The spirit which cannot die is call a soul when in the human body.  For the body without the spirit is dead. James 2:26

For the life of the flesh is in the blood: and I have given it to you upon the altar to make an atonement for your souls: for it is the blood that makes an atonement for the soul.

The thing that leaves your body once you climax :)