I put them all on auto and press the button softly for auto focus and get pictures so clear I can see the fibers on a blanket.
The only thing I've learned to manually adjust for is shutter speed. You want it fast to capture rain drops in motion and lower indoors because otherwise you're shooting a horror movie.
I've also discovered the film emulator makes a dramatic difference. You want certain ones for land so colors pop and you don't want that of people because they look like they have jaundice or high blood pressure.
They'll start to feel more natural once you start using more manual settings.
Half-pressing the shutter locks in the exposure and focus to what is calculated for that scene. So if you lock focus on a far object and move the camera in front of a close object and take the picture, it'll be blurry because the lens was focused to a farther point.
If you lock the exposure on bright day outside and walk inside and take the picture, it will be underexposed because the camera set the exposure for a brighter scene.
You should be able to lock the exposure with the af / ae lock button on the back of the camera as well. You can try using manual focus as well, there should be a switch to switch between AF / MF. When using MF you can cycle the lens' focus back and forth (not the focal length, the focus) and it'll be a good learning experience because that's how people used to focus before AF was invented.
Similarly, try setting the shutter speed dial to A and take pictures of the same thing from f1.7 to 16, you'll see the difference in the background blur that it creates.
I notice they don't make mirrored ones anymore, any suggestions for a similar camera ? I mostly take wildlife and travel photographs for myself and put up on the wall.
Great pictures; the fort one is my favorite. Nature reclaiming buildings is such an interesting thing to see and shoot.
If video is not important and you don't want to go mirrorless (so you can use your current F-mount lenses natively), you can get a used D500 (pro body with faster AF and burst features but not useful unless you're planning to shoot fast-moving subjects), D7500 (same sensor as D500 but scaled-down features) or D7200 (oldest of the three but scaled down D500 as well while still having a 24MP sensor).
Or you could get a lens based on what you want to shoot more of. Nikon basically has 2 sensors, the 24mp one in the 3000, 5000 series and the D7200 and the 20mp one used in the D500, 7500 and the Z series. Only difference is the processor and that the D3000 series can't use 14-bit RAW. F-Mount is being phased out so you can get good pro lenses cheaper in the used market now that a lot of people are switching to Z-Mount (if you live in the US / Europe / Canada that is, used markets suck at most other places besides Japan).