what villains were on this show?

I think that historically superhero TV shows have tended to NOT have the protagonists deal with threats from other super powered characters. On the two better known '70s superhero shows - "Wonder Woman" & "The Incredible Hulk" - seldom did either protagonist encounter a supervillain (and when that happened the supervillains were never ones from the comicbooks). This historical tendency is about saving money; it's easier to stay on budget (esp. for a weekly series) when you only have to create super-power effects & stunts for your main character. And villains, even for a superhero show, don't need super powers to be entertaining. If this show's producers were going to use one recurring villain from the Spider-Man comicbooks, it should have been the Kingpin. He'd have provided an imposing presence without any super powers to depict.