Mary Shelley's novel Frankenstein illuminates the ideas of being human and having sympathy through the theme of Nature vs. Nurture. Given that animals lack sympathy, shown through their evolutionary need to survive, the idea of being human and having sympathy is tightly woven together.
Essentially, to be human means to have sympathy. (For example, when people are accused of murder, they have the tendency to be defined as lacking human qualities--being more animalistic). Therefore, both ideas presented in the question are far too similar to separate.
Naturally, people must learn sympathy. Given that Victor's creature must be taught this (as shown through its narrative regarding its experience with the DeLaceys), sympathy does not come naturally. At the same time, being human does not either (if looking at being human as one who is capable of possessing sympathy). Essentially what this means is that although people are born human, it takes much more than this birth to act human. In regards to the novel, the creature acts far more sympathetic than Victor.
Victor (a "human"), acting without sympathy, abandons his "son." The creature (not necessarily considered human), on the other hand, continues to give others chance after chance to redeem themselves (think the saving of the little girl, the conversation with William, and the conversation with Victor).
Therefore, the themes of being human and having sympathy are far to related to define one as being more apparent than the other. Instead of separating them, I would suggest using them in collaboration to show that being human is defined by having sympathy for others. Through this, one could define the creature as far more human than its creator.