Thank you for the question, “Is it biblical that we create the other people in our lives with our minds?”
As one reads the Bible, the Creator God is the creator and giver of life
In Genesis 1–2, it is God who created Adam and Eve. He commanded them to have children to fill the earth. Thus the formation of a new human life is from the sexual intimacy of a husband and wife according to God’s plan. It is not form out of our minds since we are not God.
Psalm 139:13–15 describes the Creator God involvement in the formation of every human being. It is not left up to chance of a person’s biological or physiological makeup. God is intimately acquainted with every detail of one’s life even as Jesus said that God knows the number of hairs on our head.
A person may dream about their ideal job or life’s companion, but one’s dream or ideals do not make it a reality. One has to be careful not to live in a world of delusion of “making up” friends. One may feel lonely and be lonely. God has given Christians a community of believers to find fellowship and support.
SUMMARY: Christians do not have imaginary friends for there are other believers of God in the family of God. Visiting a local Bible believing church or small group is a good starting point.
For more perspectives:
https://www.quora.com/Is-it-biblical-that-we-create-the-other-people-in-our-lives-with-our-minds