It's funny that you included javascript in the list when you can literally just type javascript code in an html <script> tag and open it in the browser that comes with your OS.
You quip at flask for requiring "command line experience" then talk about PHP's built-in web server that's also a command line tool.
And let's be realistic, if you're using php without a package manager, you're either no doing anything serious or you're reinventing the wheel, and you will need to get comfortable with the command-line sooner or later anyway.
I will say that PHP is probably the the most frictionless server-side web-development language to get started with, but it's not by a huge margin.
And considering that in web-dev you're gonna need to learn javascript anyway, I'd probably consider it to be the best introductory language.