Here we propose a heat transfer framework for how human-to-human interaction spreads everything on the landscape: disease, goods, knowledge, news, technology, science, language and culture. We show that the phenomenon of "human spreading" shares key features with phenomena that are fundamental in physics (heat, electricity, species, Darcy fluid flow), which spread through continua. As example for discussion and illustration, we construct this theoretical framework by using the early phase of the coronavirus outbreak, from before May 2020. The human spreading phenomenon (S curve) is unveiled systematically by using a minimum of measurable parameters: the number of persons with whom one person comes in contact, the radial size of each step in the growth of the swept territory, the radial scale of the inhabited territory, and the directions in which infrastructure (e.g., air routes) are available for long and fast spreading. The resulting configuration of spreading is a multiscale assembly of clusters of fast channels embedded in interstices with slow diffusion. The configuration is dendritic, where each direction of long and fast spreading is covered by a finger of clusters, and each finger generates its own ramifications. The similarities between this configuration and the dendritic architectures for heat and fluid flow through heterogeneous media are discussed.