The things PHP had that made it win (for a while) was that it was easy to set up and configure for a hosting environment (Apache plus modphp worked out of the box consistently) and the HTML first design made it easy to add to static web pages, whereas forms and CGI was multiple steps and more confusing for less experienced devs.

I'd qualify that. A lot of the hype around PHP being easy for cheap web hosting misses the point that a lot of that cheap hosting was configured with PHP as a CGI module, not mod_php. In that sense it was on a level playing field with Perl.

Agreed. The one thing PHP demonstrably did better than other langs (other than be a simpler Perl) was be web-first.

Other langs assume you could be doing anything, and here's the extra steps necessary to make it serve pages. PHP assumes the reverse.