HIVs are the most studied viruses in history and the best model to understand the interplay between virus and host antiviral defence. Tracing the origins of HIVs would provide a framework for us to understand cross-species transmission and pathogenicity of SARS-CoV-2. The comparison of SARS-CoV-2 and HIVs would reveal a common theme and the requirements for their successful species jumping. In particular, lessons learnt from HIVs are highly relevant and instructive to SARS-CoV-2 for the following reasons. First, both HIVs and SARS-CoV-2 are of zoonotic origin. Second, infection of their reservoir hosts with parental viruses of HIVs and SARS-CoV-2 results in no or mild symptoms. However, when they infect humans, much more severe symptoms are developed. Third, the similarities and differences between HIV-1 and HIV-2 resemble those between SARS-CoV and SARS-CoV-2. Finally, both HIVs and SARS-CoV-2 are plausibly derived from discrete cross-species transmission events from animals to humans. Thus, we will briefly review our current understanding of the origins of HIVs and how host anti-HIV defence has shaped the emergence of the pandemic HIV strains.