The main issue with humans and their ancestors and the environment is from agriculture. We went from hunting and gathering for millions of years, skimming excess carrying capacity off the land in low numbers, to agriculture only a few thousands of years ago, where we manipulate the environment to suit our needs where we are. We just aren’t adapted to agriculture let alone modern life. Mutually beneficial symbiotic relationships do not happen overnight, nor in the timespan that we have been farming and amassing population. So long as we insist that there must be some 8 billion people living at once on earth, the biomass to fuel that massive population has to come from somewhere in the system, and considering the complexity just about anything we do is liable to have deleterious nth order effects we will never be able to anticipate until they are plainly obvious.