Not every soul (Atman is the correct terminology) that is manifested is incarnate in human form at any given time. Aside from the Atmans that are now embodied in the plant and animal kingdom, there are other spheres of existence where Atmans reside. And Atmans are consistently emanating from Divinity. The Hindu scriptures do not place an exact number of Atmans, either in the created universe or beyond.
.
Other reading material: Reincarnation: WHO is it that Travels? Atma? Jiva? Subtle body?
Relevant videos: Swami Nikhil Anand Hinduism Q & A: How many souls are there?,
Contributor: Fred Stella
Location of this post (16d): https://www.hinduspeakers.org/ufaqs/how-many-souls-are-there/