WHO is doing the "considering" here? You? Me? Aunt Tilly?
The DoI cites the unalienable right to life, not the attainment of a "level of life" where a human life could be considered "a functioning human being/person." That is, the right inheres in the life, not in the attainment of a certain level or particular stage of life.
The reason we have a rule of law, based in the Constitution, is to replace relative and often selfish human opinions/judgments with constant standards of justice and human rights applicable to all.
The only alternative is moral relativism and, therefore, no equal standards, no equal protection, no equal justice under law. This is to make a mockery of the Constitution.
Perhaps you have heard of the recent federal case, where a court barred a pregnant illegal alien from being deported because her child was conceived in the United States, and its father is American. The judge extended equal protection to that pre-born, on the grounds that it was entitled, not just to life, but also to its liberties as an American citizen. (Go figure.)
Plus you may also have heard of the so-called "Laci's Law," arising from the Peterson case in which a preborn child, Connor, is alleged to have had his right to life violated by his father, who also allegedly violated the right to life of the child's mother. Thus Scott Peterson has been charged with a double homocide.
Bad logic, again. You still are depending on function to define human being, rather than species.
The embryos at this stage can survive freezing under current technology, while later embryos and fetuses cannot. Who knows, some day we may be able to revive Ted Williams.