HIV was a very different context and isn't remotely comparable to SARS2. It took many decades for HIV to spread to a consequential base of infected persons, from which it was then able to explode across the globe (due in part to the difference in travel then vs now of course). The reason it took so long to find the animal source, was because it wasn't perceived to be a critically important virus to deal with - it wasn't a priority - in the early decades due to the very low number of cases and related deaths. Depending on which origin theory you believe, it took anywhere from ~20 years to ~60 years, for HIV to go from a small number of cases to being globally threatening. SARS2 did that in a matter of months, so the priority is far different. SARS2 has killed 5+ million people in under two years, it took many decades for HIV/AIDS to do that. The US is still seeing more annualized Covid deaths than the world had total HIV/AIDS deaths annually circa 1990/1991, and that's with 64% of the US population having taken at least one vaccine dose.

The reason we haven't tracked SARS2 back to a starting animal source, is likely because there isn't one in that it didn't spread directly from an animal to humans without modification (they sampled it from bats, then they modified the virus, from which it was able to more easily infect humans); and if there were one, China aggressively blocked all efforts to discover the origins there (including destroying vital early data about the virus), which is beyond incriminating.