Mike Myers plays two roles in Austin Powers: the titular spy and his archnemesis Doctor Evil. Because one of them is a hero and the other a villain you would expect them to tell different types of jokes, but it is surprising how different their contributions to the movie are. If you consider them closely you can see how they suggest two divergent paths that the story could have taken - one pushing the film towards being more of a middle of the road movie and the other pushing it to becoming more of an absurd underground movie.
The Austin Powers character tells almost no jokes - he mostly has catchphrases that aren't funny by themselves, but are delivered with a broadness and exaggerated emphasis on Myers' part that conveys "this is a punchline!!!" When Powers wakes up after 30 years in a cryogenic freezing tube he has to get up to speed on what he missed in between 1967 and 1997, but most of the gags related to his crisis are really obvious and toothless - they reference broad social changes like women's liberation, or really easy targets like tacky 60's fashion. Basically, a movie that was only about Austin Powers would be nothing but mugging, but I could see that movie becoming popular with a broad (and theoretically undiscriminating) audience.
Doctor Evil, on the other hand, has a lot of really weird facets to his character. The interactions he has with the son they made from his DNA while he was frozen are specific in a way that the Austin Powers scenes aren't; although the idea of a super villain in group therapy is kind of low hanging fruit, the writing choices made in those scenes explores a villain's psychology in an interesting way, exploring the particulars of his psychology in a way that grounds his (mostly ridiculous) character. More importantly, the changes that he has to acclimate to aren't cheap references - the fact that his evil plots to discredit the British royals or to destroy the ozone layer actually happened while he was slumbering are not only less obvious than the fashion jokes that the Powers character embodies, they also make political points that are compelling because they suggest what a bad job we've done of taking care of the world in the last few decades. Basically, a movie that explored Doctor Evil without Austin Powers would have been a much more interesting movie, but it would have also been more subversive and probably have ended up being a cult movie but not a big success.
Instead of making a movie with just one of those two characters, however, Myers put them both in the same movie together and split the difference between the two tones they bring to the table. The series eventual fate follows a logical path from this first installment: the sequel doubled down on the catchphrases, helping it to become massively popular, but then a lot of the little bits of weirdness that redeem this first one got washed out, leaving everyone worn out by the time the third movie came out. I think Doctor Evil two would have been a lot better than Austin Powers two ended up being - but I also think that they would have never made Doctor Evil 2 because the first one probably would have bombed.