Without plants, life on earth would be confined mainly to mushrooms and algae. Everything else that is alive on this planet is dependent, directly or indirectly, on plants. Given this fact, it is accurate to say that plants have given humanity everything, since without them humans would not exist.
Everything that humans eat is either a plant or derived from a plant, with the exception of peripheral items such as salt. The animals that some humans eat are themselves dependent on plants for food. Plants can be produced for food directly in a backyard garden, or can be bought from others who have grown them and processed them into commercial food. The simplest way to acquire plant food, and the way that humans fed themselves for most of human history, is to forage for wild food within nature.
Oxygen is a by-product of the plant life cycle. While animals breathe in oxygen and breathe out carbon dioxide, plants do just the opposite: they intake carbon dioxide and excrete oxygen. Without plants, animals would have no oxygen to breathe, and life as we know it would be impossible. Plant-rich environments naturally create cleaner and healthier air; this is one argument for the existence of large parks within urban areas, to counterbalance in a small way the degradation to the air caused by automobiles and other polluters.
Because humans evolved from their very beginnings surrounded by plants, we have developed a very deeply rooted aesthetic appreciation for plant forms. Most people appreciate the beauty of plants, whether in the form of small domestic touches such as flowers and houseplants, or in the form of vast forests and wilderness. The beauty of plants can be naturally occurring and untouched by the human hand, or the result of very refined culture, such as the tradition of bonsai trees that developed in Japan. The beauty of plants has been a central factor in many aesthetic traditions for thousands of years.
Topsoil is formed over many years through the rotting and decomposition of plant life. This topsoil in turn is the basis from which new plant life appears. Although animal life also contributes to topsoil, the sheer biomass of plant life on the surface of the planet means that the majority of topsoil is the result of plants that have lived, died, fallen back into the soil, rotted and contributed to the ongoing fecundity of the Earth.