The human zygote is a distinct human ORGANISM. Are you trying to persuade us that that ORGANISM transmogrifies into a separate human ORGANISM at some magical even called implantation? ... And with artifical wombs, 'mother' may be a machinery complex before too long.
A newly-fertilized zygote or embryo contains everything necessary for growth in its 'static state'. It can be frozen in liquid N2 and remain so indefinitely, and yet later be thawed out and implanted, and develop into a birthable baby. The zygote/embryo at that stage contains everything necessary to start up all the life processes that will be required for full development, so even if essential processes are frozen the embryo can remain viable.
By the time the embryo has finished implanting, the 'static state' is no longer sufficient for life. Its dynamic state becomes critical. Once everything is in motion, it must remain so; some processes can be restarted if they stop briefly, but others cannot.
By what definition is an embryo sitting in a tube of liquid N2 "alive"? It does not grow, nor change, nor metabolize anything, nor reproduce itself. If it is thawed out, it will have the ability to do these things, but for the duration that it is frozen it will do none of them.
I would posit that the difficulty is with the notion that everything must be "alive" or "dead". I would posit that it is possible for something to be "viable" and yet not fully alive yet.