The cells are human. That, of course is undeniable. But so, then, is my gall bladder and appendix. I'm not opposed to having them removed or discarded when necessary.
What is your source that "brainwaves are detected very early in stages of development?" I'm confident that if you go to these sources, you'll find that brainwaves are detected when there is a brain. This, of course, isn't until far beyond the stage at which embryonic stem cells are harvested.
Moreover, you, like many others who are opposed to embryonic stem cells, have yet to address why there is an objection to using blastocysts destined for disposal (i.e. never to become a people) aren't put to good use. The answer, as I've demonstrated, is superstition. Pure, unadulterated superstition.