Human nature is not fixed. We are capable of self-serving acts, selfless compassion, and uniformly harmful acts that neither help ourselves nor others. We evolved as social animals, but that can mean unconditional compassion toward all beings, or simply toward those within our "tribe". Besides, we also evolved to adapt to our surroundings, and because of that, civilization has been able to thoroughly reshape human nature, in both good and bad ways.

Instead of worrying about what human nature fundamentally is, think about what human nature should be, or what it is at its best, and try to embody that. That's not to say you should attempt physically impossible things, or ignore your needs and emotional realities, but you should use your ability to adapt and change to the benefit of yourself and the world. Be compassionate, and help build a society that will continue to produce compassionate humans.

Also, I had cereal.