The main point of a DSLR is to give the photographer
a lot of options, so the photographer can use their skill and knowledge to adapt to the situation and make the photo that they want to make.
Sometimes you want shallow depth of field, sometimes you want massive depth of field, sometimes you want a dark photo, sometimes you want a bright photo, sometimes you want motion blur, other times you want panning blur, or no blur at all, sometimes you want warm or cool colours, and so on and so on.
In full Auto mode, the camera makes these choices for you and gets results that are acceptable but rarely spectacular. The scene modes are a little more specialized and can give you better results. P mode is fairly automatic, but gives the user some options. Av and Tv modes give you more finesse to choose what you want. Finally there is M, which is not used always, but can give you results no other mode can, if you know exactly what you are doing.
So, start learning
Plenty of books, blogs and youtube videos. Start with Exposure, then learn what Aperture and shutter and ISO do, what effects they have, and how to manipulate them. Until then, use the Scene modes and P mode. Note that some scene modes are on the mode dial, but some more are selectable within the SCN option.