Actually, as I recall, the GUI was more an outcome of Xerox in early 80s. Apple picked it up from there (mid-late 80s) and Microsoft followed. Depending on your definition of "GUI", first MS GUI was Vista; although some accept Windows95/NT as a GUI.

Interestingly, what we know as html began life as a creation of Apple. It was picked up and incorporated into the "internet" by Warners-Lee with his research in Bern, Switzerland to connect disparate computer systems and share information. Yes, that was a few years before Al Gore "invented" the internet.

AOL first surfaced as iVillage, an offering from Apple.

Netscape arose from a research project through the Dept of Energy site in Illinois.

Microsoft Explorer was the original base that spawned Netscape. MS could not "sell" it as it was public domain with the MS Explorer face.

Late 80s and early 90s were some interesting years with the growth of the internet and the publicity battles that raged. Many quality products failed to catch on due to lack of "marketing" support.