WSGI server vs Web Server

[snippsat]

s a HTTP to API interfacer. if i got that right,

Look at Full Stack Python WSGI Servers for more info.

then i still need to learn it, eventually, to do web development (as opposed to using an existing framework).

Using WSGI directly for web-development is not a pleasant thing,people who want to create yet another Python web-framework most read the WSGI specification.
There is no need at all for user that want to do web-development in Python,to read the WSGI doc.

Look at Werkzeug it's a thinner layer over WSGI.

Werkzeug is a comprehensive WSGI web application library.
It began as a simple collection of various utilities for WSGI applications,
and has become one of the most advanced WSGI utility libraries.

From Werkzeug came Flask same Author Armin Ronacher now under Pallets Projects with more developer that keep stuff updated.
With Flask work close to HTML/CSS/JavaScript with very little over head,it's very pleasant to do web-development in.
Django is also good,but it's has an other model that Flask with a lot stuff build in even if need it or not.