In a normal world with enough biodiversity, it's balanced, some species can die, newer comes. In a human society whole ranges of species are killed because human have such an impact, insect mass is 10x less than 30 years ago, the problems is certainly not too much insects, it's the opposite, their lack of habitat too because we put concrete, roads everywhere, so instead of trying to fight directly and incorrectly these diseases, it's much better to fight the source issue, reducing car traffic, reducing/stopping air traffic, maritim traffic, etc..
Uh, normal ecosystems are rarely what humans would call balanced for long. There are regular die offs, population booms and busts, plagues, etc, all the time in untouched ecosystems. (Hell, just look at ‘red tides’).
Some human impacts make things worse, some make things better - depending on the criteria used.
For instance, draining swamps is a classic human behavior that dramatically decreases disease vectors. It also removes habitat for a large swath of animals, including alligators.
Overall a good thing, or a bad thing?
It’s rare that things like frequency of car or truck traffic has much bearing itself, though making roads definitely can.
Do you have examples where human presence help the environment?
I don't know some, obviously there are constant changes, normal ecosystems are strong due to their biodiversity, so they recover and adapt quicky. With humans there are holes, more room for strong diseases. It's like on a more local scale the health of an average rich country human, it's very weak and subject to diseases, because of a bad lifestyle. If for a decade this lifestyle is changed with more diversity, interaction with nature, the change is incredible, it's the same at larger scales
