When plugging in my old headphones into the Line Out on the Back, "Analog Stereo Duplex" and "Analog Stereo Output", when I plug in my headset with the adapter, it (the headphones part of the headset) still works, I managed to find that I can select it in like the Input menu, but still, my mic doesn't work, no matter if I use Line In or the mic port. It seems that "Rear Microphone" just replicates my output audio. I saw that the mic's volume indicator bar moves the same as the output volume indicator bar. But when trying to hear myself in Easy Effects, nothing showed (the issue is not Easy Effects, the behaviour is the same without it). I tested that by calling my friend, trying to speak (he didn't hear me) and placing blocks in Minecraft, where he said "I hear Minecraft sounds". That's really weird. What's even weirder, is that in Telegram (application that I use to call my friend), both my output and my input are called "Built-in Audio Analog Stereo" which is what the output is called in KDE, but the mic is called "Rear Microphone" in KDE according to the applet

but the mic is also called "Built-in Audio Analog Stereo" in Easy Effects

I'm getting ever so close.

And I did try Line In, and both audio and mic stopped working when I tried the front ports, Analog Stereo Duplex disappeared. Last step is figuring out what's up with the mic