The problem with Horcruxes is that they have a piece of soul and all memories. This is no problem in an item that is to be used to keep the main soul alive in this plane. Or if set up to recreate a body for the soul fragment. The big problem, not written as no one did more than three, Is that it only works if you have at least a quarter of your soul. So the Diary, yes (1/2 soul), the Ring would have been yes, but the Hollow was able to absorb part of it, dropping it to one fifth, instead of one fourth. So the curses got more powerful, but the soul got weaker. Now we reach the Snake, the fragment decided that staying with Tom was safer for it. The miniscule piece that broke off, not even a full half of the (0.015625); decided it did not want to die. It knew its main piece would try to kill him. Having the blood protection and realizing that the old magic; possibly religion, was useful, changed the one and (.005625). This small section was not aware enough to try to take over, the blood ward Lily did was an ancient protection of offering themselves for another. The baby Harry never cried. By age two, could talk as well as most adults.