And you are confounding those meanings. No concept of evolution considers human beings to be improvements over protocells! The notion of evolutionary "improvements," by which you really mean "relative advantages," is something that applies within populations, and has relevance to the outcome of interspecific competition, but I don't see how it applies across lineages over time. Resistance to malaria gives one phenotype an advantage over other phenotypes in the same population under certain conditions. Placental mammals had traits that gave them certain competitive advantages over sympatric marsupials. Human beings would be at a decided disadvantage under the environmental conditions in which early bacteria thrived, don't you think?
And, just to remind everyone, human beings are not the only pinnacle of evolutionary success, despite the "protocell to human" type of label that creationists, and only creationists, like to use. Every organism alive today, according to current evolutionary thought, is descended from that original protocell line, and it would probably be helpful to keep in mind that we're not talking only about "protocell to human," but also "protocell to dandelion," protocell to chanterelle," "protocell to bacterium," and so on. But these lineages are not completely independent of each other; that is, humans and dandelions didn't spring independently from the same protocell ancestor. The simplistic "protocell to protestant" labelling does a great job of obfuscating the issue.