How Imaginary Numbers Emerged From Solving Cubics

HN recommends it as a well-visualized, story-driven history of complex numbers, suitable for beginners; some quibble with its framing of algebra and geometry.

Veritasium tells the history of how imaginary numbers arose from the quest for a general solution to the cubic equation, including the duels and secrecy among Renaissance mathematicians. It argues math had to give up the requirement that it mirror reality.