The two reasons why we must preserve the remaining tropical forests is because this way we can also preserve species that live on it, such as animals and plants, but also it is necessary for us to preserve it to have a natural barrier between us and diseases that can come up after deforestation due to a higher exposure of different species to microorganisms (such as pathogenic virus and bacteria) they do not evolved with, including us, as human beings.
A way that people can use tropical forests both to protect them and to utilize them is through ecotourism, since this way we can spread the voice on the importance of this, and also produce economic benefits of these practices.