Regenerative in the personal, social, and political sense refers to "making things better" - or improving from a more degenerated state into a more healthy, wholesome, lasting, and productive state. This includes healing fragmented people psychologically, producing social justice, and improving the environment. Regenerative implies 'growing' in life as opposed to approaching death.
The point to be made with respect to creating advanced civilization is that there are many aspects in which society and nature have been degraded through human history. These ills can be made better - and a regenerative society is one which focuses on improvement of these issues. These issues include anthropogenic conversion of forest to desert, species die-off, or farms that keep mining soil after having killed off the Soil Food Web. The issues also include social issues, such as the disparity between the rich and poor, lack of access to education, or alienation of people from doing what they love.
Thus, the essence of OSE work is regenerative development - making things better for people and planet. The way to act on this is starting with one's own work. If it is a regenerative livelihood, it solves the issues mentioned above.