The quesiton may seem weird so sorry in advance So suddenly an opportunity arose to go to a very cool game jam nearby next week and I wouldn't want to be completely clueless there so right out of the blue, I need to speedlearn some free 2D game framework/engine for PC games to the extent that would allow me to be able to put something together during the jam

Now, I've been programming for quite a few years now so this side isn't scary to me (though my interests are most likely data mining and machine learning related). I have experience and feel confident in C++ and Python, though any language will do and I don't have preferences there.

As far as engines are concerned, I've only dabbled an hour or so in Unity once (did the very first tutorial from their site) and put together a game or two (very basic ones) in Game Maker: Studio. Also played a bit in Unreal Engine 4 but I'm not sure it's the best fit for 2D.

What engine/framework/however_it_is_calles would you suggest if I only have ~4 days to learn and would like to learn as much as possible? I know I won't master anything but I'd like to go in the right direction to not get stuck in the beginning, so something with a nice learning curve in the beginning would be cool Since I'm deeply in love with Python, I was thinking about Godot. Anything better comes to mind?

Given your constraints and your love of python, I'd say Godot is your best choice.

If you have already created basic games in Gamemaker Studio then why do you want to "speed learn" a new engine in 4 days?
Just use Gamemaker.

Serapth - yeah, I decided to go with Godot :) Thanks for recommending your tutorial series, that's my plan as well - currently I'm reading through the official wiki tutorials and then (probably tomorrow) I'm planning to watch some of your videos :)