In Jeshen Space, there are three main popularly held opinions for why Jeshen and Humans look so very much alike:
Like a Tasmanian Wolf and a Gray Wolf, the two species evolved to be externally very similar because of similar successful responses to evolutionary pressures, despite their dissimilar origins. Humans and Jeshen just happen to appeal to each other.
Some advanced culture pushed Humans and/or Jeshen to evolve their external similarity in their respective prehistories, for unknown reasons. They were designed to appeal to each other.
Many religious folk believe that god meant for Jeshen and Humans to find joy in each other’s company. They were meant to appeal to each other.
There is no conclusive evidence for any one of these opinions. Most people don’t ever think about it, and just accept it.