A bad feeling about first published papers
You should do nothing other than continue growing and learning. The most common reason would be #1. I can't say the most likely reason is #1, not having seen the papers. 

But a lot of authors, even poets, look back on their early work with a sense of wonder about how they could have been so naive. It is a sign of growth. 

Yes, #2 is probably also a factor to some extent as CS has been a fast moving field overall, not being much over 60 years old, compared to, say math and such. 

And you haven't said that the papers are actually wrong, just a bit naive. Hopefully we all learn some things as we grow older. It normally happens because we are actively thinking about things. 

Others at the time (reviewers, editors, advisors) thought that the papers were fine for the time. They were fine.