>>113366496He'd probably fit in better powerlevel-wise with Marvel, where there are way more mid-level heroes. Star Platinum's strength, speed, etc. seem to be more or less on Spider-man's level, if not a bit higher. Add to that the ability to stop time for a few seconds and Jotaro's capacity for quick thinking, and I imagine he'd sit pretty comfortably near the top of street tier alongside Spidey.
>>113366935According to Araki, part of the reason he was so distant from Jolyne and his wife is that he was off fighting evil Stand users. He also took notice and sent Koichi to investigate activity that might've related to DIO, even though it didn't really impact him personally. After Part 3, it seems like he developed into a more proactive character who was broadly concerned with evil in the world.
You could argue that he wouldn't typically care about problems that don't involve Stand users, but there are plenty of superheroes who sort of act as "specialists" in that regard.
>>113379500Not unless he had a Kryptonite dagger to hide and stab him with during time stop. Star Platinum's most impressive feats of strength that I can remember are derailing a sixteen wheeler truck with a single punch, and keeping a road roller from crushing Jotaro while a super strong vampire was driving it into the ground. And while he's fast (even without time stop, able to react to bullets at point blank range without any apparent difficulty), he's several orders of magnitude below the likes of Superman or the Flash.