I've been thinking about this a lot and I think our car-focused construction patterns are to blame. In my state we have a grid of roads (whether paved or unpaved) that covers pretty much the entire state. It seems like where the roads go, people will go build. Everyone wants to have their own quiet area and when everyone does it (enabled by the automobile), we end up with incredibly fractured habitat. I think the only real solution is for governments to stop allowing sprawling, car centric, development and possibly get rid of some roads in rural areas. Doing that without impacting wealth might be tough. However, there are plenty of places where roads go that do not need roads. At a personal level though? People underestimate the impact they can have in their local government.

If you are in the US:

https://wildlandsnetwork.org/ https://rewilding.org/

You can also contribute to local and regional land trusts:

https://www.landtrustalliance.org/

If you own land, you can will it to a conservation land trust. Encourage friends that own land to will it to a land trust.

Have less/no children. Donate to family planning organizations.

at your level? consuming less resources. It's quite easy to lower your environmental footprint by a half, by changing and reducing consumption habits (eating less or no meat, no pets, avoiding to own a car if possible or at least not a heavy/polluting one, no cosmetics, soap bars instead of bottles, reusing, repairing everything, ..). If everyone in developed countries do that, it's virtually twice less people on the planet, and the environment will be much more likely to catch up in the short and long term

and voting for the right people, but I don't believe much in politics for the moment, on this problem

You've a very sane reaction I want to say, I hope most people will do too as quickly as possible