Some characteristics of 'life' include metabolism, growth, reproduction, response to stimuli, adaptation. Inanimate material, like 'star dust', possesses none of these characteristics. It does not matter if they did, if they will, or if inanimate material like it did, does, or will. What is considered life is based on our definition of the word life. Sperm and ova fit into that definition, 'star dust' does not. Further, humans do not arise from molecules, they are composed of molecules. A diploid human life arises from the union of two haploid human lives which in turn individually arise from other diploid human lives, et cetera. That which we call 'life' is present at every step.