I don't know if anybody has learned anything from wars passed, except for what mistakes to avoid. The bottom line is war is part of us humans, once it was tribes vs tribes, then it became town vs town, nation vs nation, alliance vs alliance, faith vs faith, and so on and so forth... That's who we are, anybody picturing a world without wars is picturing an utopia. Even if one day we all unite under one global government (not that I see this happening anytime soon) wars won't be gone for good, they'll just be different, smaller scale, guerrilla-like conflicts based on the same principle that's driving all wars: you got something that I want and the easiest, or the fastest, or the only way for me to get it from you is to club you to death or bomb your @ss, so that's exactly what I'm gonna do.
So yeah no reason to deny who we are, we are not the keepers of the peace in the galaxy, we're just a species that wages wars from time to time, nothing bad and shameful about it. Just look at our history, it's full of wars from ancient times till today and it will be so in the future as well, maybe not so frequently, maybe not in huge WW-style scale, but there will always be war in one form or another for one reason or another.