Just as the combination of many strong and weak, visible and invisible forms of energy gives rise to waves in an ocean, the Brahman/Atma (energy, soul is not a right terminology) gives life to entities around us and including us. Why were the waves created? We don’t know. Why were Atman created? We don’t know. It just is.
GOD didn’t create Atmans. Atmans existed in the past, exist in the present and will exist in the future
na jāyate mriyate vā kadāchin
nāyaṁ bhūtvā bhavitā vā na bhūyaḥ
ajo nityaḥ śhāśhvato ’yaṁ purāṇo
na hanyate hanyamāne śharīre
The Atman is neither born, nor does it ever die; nor having once existed, does it ever cease to be. The Atman is without birth, eternal, immortal, and ageless. It is not destroyed when the body is destroyed.
Other reading material:
Relevant videos: Swami Nikhil Anand Hinduism Q & A: Why did God create souls?
Contributor: Rajeev Singh
Location of this post (16c): https://www.hinduspeakers.org/ufaqs/why-did-god-create-souls/