As other have said, relax, and take it easy.
With all the data on the internet, it can be like drinking water from a 5 gal bucket. Way too much data to absorb.
There is NO ONE best exposure mode. It is up to the photographer to select the best mode for the situation. There is a skill that is called into play is determining which mode is best for a particular situation.
I usually shoot in P (program) mode.
Then I shoot in Shutter priority (Tv for Canon), Aperture priority, or Manual based on the specific situation, if it calls for it.
I do NOT shoot in Auto mode for 1 reason. In Auto mode, the camera will autofocus on the
closest subject/object. This means that when shooting guests at a dinner table, the camera will focus on the dinner table between me and the guests on the other side. So
you cannot have anything between you and your subject, or the camera will focus on it.

Shooting in P mode, lets ME choose where to focus.
As long as you understand the limitations, feel free to use it, just know when to NOT use it.
The other thing to look at are the scene modes.
Scenes are the camera manufacturers attempt to make it easier to use the camera. A scene will configure the camera to what the camera manufacturer thinks is best for that shooting situation. This takes a lot of the detailed configuration out of your hands and into the camera and makes it easier to shoot different subjects and situations. This is GOOD stuff, don't ignore it.
Now . . . for shooting in Manual
Look up the "
sunny 16 rule."
It is an old film guide to exposure, when there was no automation and everything was manual. In the "old days of film" there was a piece of paper in the film box, with this info on it, and that is what I used to set my camera. No light meter, no automation, just a piece of paper to tell me what to set my camera to. I had the small version taped to the back of my camera.
The start of the rule is the exposure on a sunny day; shutter speed is 1/ISO of the film, aperture = f/16.
So with ISO 125 film (or digital setting), shutter speed = 1/125 sec, aperture = f/16.
If you raise the ISO to 500, shutter speed = 1/500 sec, aperture = f/16
The sunny day constant f/16 is why it is called the sunny 16 rule. The shutter speed changed based on the ISO speed.
From this base, there are adjustment for cloudy sky, open shade, and deep shade.
The neat thing about digital, is you can look at the back of your camera, and see if you need to adjust up or down, then take another shot.
Now go out and try this.
Gud Luk and hang in there.
You will make it.
Just take small steps, and don't get overwhelmed.