Those questions you pose is not really of scientific domain - they are actually equivalent reformulation of the religious question when/where "soul" is created (equivalence of the "soul" and "human" questions is established by the religious dogma that only humans have "soul"). Science has Cro-Magnons, Neanderthals, Australopithecus, etc... It is the question of religion domain whether Neanderthals or our common ancestors all the way to ancient apes were "humans"/"had soul". If notion of "soul" exists where did it appear between us and those cells $2B years ago to which each of us is connected through the continuous chain of bodies?
We know when the body begins to develop (conception), but we're uncertain as to what sensory input is being processed, whether that program is aware of its own state, and such things may vary between individuals.
We have bright lines, but none that have sufficient agreement about their use in all cases for legal purposes.
The hard part is in forming the laws and deciding whether they should value undeveloped members of the homo sapiens genus for their species, for being intelligent, their capacity to suffer, or other reasons, then balancing whatever rights are assigned against the rights of others.