The 1st 2 pics are Pothos (Epipremnum aureum.)
The 3rd pic is Schefflera arboricola (dwarf umbrella tree/octopus plant.)
4th pic is another Pothos.
The soil in all of your pics looks really dense/muddy. A more porous, chunky soil (like cactus/palm, if one is buying bagged,) can have air in it even when it is moist. Roots need oxygen and moisture at the same time to function. When there are tiny particles of any kind in a pot, such as peat, sand, silt, clay, they filter into all of the tiny spaces in a pot, eliminating the air. "Overwatering" is the label and manifestation when roots have suffocated and/or rotted, combo of both. There is no one thing folks can put in to make soil better, but removing tiny particles of any type will definitely help. Over time, organic bits decompose into smaller bits, so even the "best" soil, if it has organic components, will need to be replaced when this happens. The speed at which this happens depends on many variables, but on average, about 1-3 years. Adding quite a bit of perlite to potting soil works well for many people/plants.
