The trouble is that "human" is a very ambiguous word. If a "human" is a living organism made out of cells with DNA typical of humans, then certainly embryos are

The trouble is that "human" is a very ambiguous word. If a "human" is a living organism made out of cells with DNA typical of humans, then certainly embryos are humans. If a "human" is a thinking, language-using, tool-using bipedal mammal, then certainly embryos are not humans (but neither are 3-month-old babies). There's nothing wrong with that ... except that most of us have strongly held beliefs about "humans", which don't necessarily come with precise definitions of "human" attached to them.